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Archive January 2010

If I was a running shoe manufacturer, I would be worried… aimee whitcroft Jan 28

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This is brilliant.  I’ve heard intimations of it on various websites for the last few months, but it’s always good to see a published paper backing it up.

running shoes

In short, it says that running shoes are not actually necessary for runners.  In fact, they may do more to cause damage than to protect.

So, the paper, published in Nature, says something along the following lines:

Man has evolved as a creature capable of running.  For long distances, on often very hard (and by that I mean the opposite of squishy) terrain.  If you don’t believe me, simply look at the runners in, well, large parts of Africa.

People running barefoot generally land one of two ways – either on the front/balls of their feet, or else using a ‘mid-foot strike’ in which both ball and heel land simultaneously.  This allows the complex feat of structural engineering that is the human body to absorb most of the shock of this impact – the moment when, apparently, running can cause the most injury.

However, running shoes change the gait of a runner substantially.  By lifting and cushioning the heel, they elongate a runner’s stride, meaning that the impact of striking is the ground is borne by the runner’s heel. and then ricochets upward.  This, in turn, leads to a huge amount of jarring – some 1.5-3 times the weight of the runner, much of which happens to the lower leg.  This could help account for the impact-related injuries which are experienced by many runners these days, including tibial stress fractures and plantar fasciitis.

(Also, the arches of one’s feet, whose primary purpose is shock absorption, apparently flatten over time.  Everyone who wears heels often will be familiar with this problem.)

In order to come to this determination, the researchers looked at three primary groups of people – those who have always undertaken endurance running using athletic footwear (1), those who grew up running either barefoot or minimally shod but now use running shoes (2), and those who grew up using running shoes but now run barefoot or minimally shod (3).   They also compared two other groups of people – those who have never worn running shoes (4), and those who have grown up habitually wearing them (5).

What they found was this:

Groups 1 and 5 (the habitually heavily shod, as it were) generally hit the ground with their heels, both when running with and without shoes.

Groups 2 and 4 (the originally unshod) generally landed on the balls of their feet in both situations, and occasionally used mid-foot strikes (when shod in group 2, and unshod in group 4)…

barefoot

Credit: Benton et. al.*

“This image compares two Kenyan runners from our study at the moment just prior to foot strike plus representative force traces below. The subject on the left has been shod most of his life and lands on his heel (a rear-foot strike)l, causing an impact transient: a rapid, large collisional force within a few milliseconds of impact (not unlike being hit on the heel with a hammer with a force several times one’s body weight). The subject on the right has never worn shoes and lands on outer the ball of her foot before bringing down the heel (a fore-foot strike). This kind of landing is comfortable without shoes because it avoids any collision. The paper explains why forefoot and some mid-foot strikes avoid collision forces at impact.

The upshot of all of this, after looking at all the maths and stuff, is this: your body has been designed, through the millenia, to run either barefoot or with just enough of a sole to protect your feet from the glass shards and goodness-knows-what-else that is such a feature of the modern urban landscape.  Wearing running shoes could, in fact, lead to stress injuries.

A caveat, however: for those of who count yourselves as being amongst the habitually-shod, don’t simply throw your shoes away and begin your new, natural regime immediately – you will need some time for your body and gait to readjust to this new (yet very old) way of doing things.  As with all sports, take it slowly.

And, of course, the money you were saving for that very expensive pair of [insert name here]-branded shoes can now be used for something else.  Like sending me a real cocktail, across teh interweb, to say thanks.

For more details, I’d suggest having a look at the paper.  If nothing else, it has plenty of pictures of differently flexed feet and ankles, and maths, for those who’re into that kind of thing…

Reference:

* Lieberman, D., Venkadesan, M., Werbel, W., Daoud, A., D’Andrea, S., Davis, I., Mang’Eni, R., & Pitsiladis, Y. (2010). Foot strike patterns and collision forces in habitually barefoot versus shod runners Nature, 463 (7280), 531-535 DOI: 10.1038/nature08723

ResearchBlogging.org

What would we do when the aliens land? aimee whitcroft Jan 27

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According to Nature, we’d be in trouble…

radio telescope

I love it when serious publications take a walk into the slightly more whimsical.  Let me clear, here – I firmly believe that there is intelligent life out there.  I also firmly believe the hallmarks of their intelligence are that they haven’t contacted us (in the same way that one does not hang out with a revolting teenager for fun), nor are they currently involved in any activity involving probes, crop circles, or anything else.

Ahem.  Moving on.

So, Nature says that no government actually has any serious plans set in place for what to do should Xr’aHG and his mates come calling.  SETI (whose  was the first distributed computing app I ever played with back in university) have the only framework, it would seem, for what do in the case of contact (of the distant kind, not the ‘they’re actually heeeeerrrreeee’ kind).  It suggests caution and restraint.  Of course.

Many believe that the aliens might not necessarily be friendly.  Says the article:

“Palaeobiologist Simon Conway Morris of Cambridge University, UK, warned of the possible consequences of detecting extraterrestrial life. He cited examples of convergent evolution in the Earth’s biological history as evidence that there are a limited number of solutions to sensory and social organizational problems. Alien senses could be similar to human senses, he told participants, and social life elsewhere could be as violent as on Earth, where leaf-cutter ants pillage and plunder, and humans wage war. “If the phone rings,” he says, “don’t pick it up.”"

I’ll admit I’m skeptical, but fair enough.  Certainly it’s something to consider.  And the subject put me in mind of this article, which I read years ago, on much the same subject – although more oriented to the actual visitation thing.

I still tell people how amused, appalled, and yet completely unsurprised I was at the tactics that would be used should someone with different bits pop round for a beer, a light snack, or perhaps the recon for imminent world domination.  Said tactics include having the vehicle in question confiscated and removed as far as possible, on the assumption it’s nuclear powered; and having our visitors handed not one single gift, but instead handcuffed by an FBI agent in a serious biosafety suit and then carted off to a lab to ensure he/she/it doesn’t have anything gross or potentially infectious (my knowledge of microbiology suggests this would be extremely unlikely, but yes).

I’ve no doubt that these tactics would be unlikely to endear us to our visitors.  On the other hand, one assumes they would have checked us out a little before coming to see us, and so would not be overly surprised. Then again, who knows?

Perhaps they’re just biding their time until we’re ready to be a bit more mature about the whole thing…

Postscript: A little box underneath the original PM article talked about a ‘taskforce’ which had been put together comprised of interesting people who’d be assembled in the case of contact, having among their ranks mathematicians, physicists, biologists, linguists, and of course Carl Sagan.  I still wish I could be the exobiologist that gets to say hello (in the nicest, least vivisectionist of ways) to any visitors…

A little bit of fun: how to (mathematically) park your car aimee whitcroft Jan 26

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One wonders if this doesn’t have IgNobel potential.  Of course, it’s not particularly useful, so I doubt it, but it does have that slightly silly appeal :)

Vauxhall Motors commissioned a University of London researchers by the name of Simon Blackburn to figure out how much space any given car needs to parallel park without ‘see-sawing’.

As he says in his paper:

“I want to parallel park, and I’ve found a space. The road is wide, but the space looks narrow. I’m not interested in shuffling back and forth to get into the space: I want to reverse into the space at full lock, and then drive straight forward into the middle of the space to park. How narrow can the space be so that I can do this? This report uses some straightforward geometry to compute the smallest length that the space can be.”

And the final equation, which he came to using some circles and a bit of Pythagorean goodness, looks like this…

parallel parking 2Where:

  • r is the radius of my car’s turning circle (curb to curb)
  • l is my car’s wheelbase, defined as the distance between the centres of the front and rear wheels
  • k is the distance from the centre of my front wheel to the front of my car, and
  • w is the width of the car in front of mine once I’m done parking

parallel parking 3

(npr’s got some good graphics here)

So yes, folks, there you have it!  Of course, much the same effect can be achieved by practice, and various other techniques, but it’s good to know that, given the time, equipment and facility for maths almost no one has while attempting to parallel park, you could be absolutely certain whether that gap was big enough…Happy parking!

Stunning visions of Mars aimee whitcroft Jan 26

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Humanity is now the proud owner of some 13,000 photos of Mars taken by NASA’s Mars Reconnaissance Orbiter.

HiRise polar capMonitoring Seasonal Albedo Patterns on South Polar Residual Cap (ESP_014405_0945)
Credit: NASA/JPL/University of Arizona

The photos were taken by the most powerful camera of any on NASA’s spacecraft – the aptly (if dryly) named High Resolution Imaging Science Experiment (HiRISE).  The HiRISE site not only lets you amble through the collection, but also offers wallpapers (for the particularly geeky amongst us) and gives some great detail about each photo, including exactly where (as hosted, amusingly, by Google Maps), and what the local time was…

Of course, for those not as interested in the thought of hours spent wandering the archives, have a look at Wired‘s ‘best of’ to see some of the strangest and most beautiful.

And, best of all, NASA wants to hear what you, the public, would like photographed next

Sperm of a feather clump together aimee whitcroft Jan 22

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I’m gobsmacked.  And highly amused, as well (it’s the immature part of me, apologies).

deer mouseCredit: Phil Myers (photographer, copyright holder), Museum of Zoology, University of Michigan.  More info here and here.  (I tried to find a picture of sperm in question, but nothing seemed to be (c)-free)

Research published in Nature this week has shown something incredible – sperm may not be the mindless automatons bethought by many of us.

Instead, researchers have found that the sperm of deer mice (which are notoriously slutty) are actually able to differentiate between their siblings (i.e. spermies from the same male) and the sperm from competing, and hence arch-rival males.

And how do these family-focussed sperm then deal with the situation?  Not with insults, no, nor the smashing of the headlights of each others’ cars. After identifying the sperm most genetically related to them, they then clump together, allowing them to swim faster towards the egg than less cooperative/clumped together sperm.  Fascinatingly, it’s not a binary relationship – i.e. sperm from same male vs all other sperm.  Sperm were more likely to, for example, aggregate with sperm from their male’s'sibling than with those from an unrelated male.

The behaviour has clear links to the promiscuity of the species – sperm in the Oldfield mouse (a related monogamous species) aggregated without any preference for relatedness.  So why the difference?  Well, one hypothesis posits that aggregation allows the sperm to swim faster, or navigate obstacles better (the mind boggles) – in largely monogamous species which sperm hang out with which clearly isn’t an issue.  As one might expect, however, in species where the sperm of multiple males is vying for the same egg, it would be far better to give a hand up to sperm which are related to one, as opposed to helping out one’s opponents.

Another hypothesis is that the Peromyscus genus was originally promiscuous and that sperm aggregation arose before the two species (deer and Oldfield mouse) diverged, but the ability to discriminate only developed afterwards.

And it would seem to be a clear function of adaptation through sperm competition.

The mechanism which allows this clumping is simple – whereas human sperm have rounded heads, these sperm actually have hook-shaped heads.

Of course, the scientists are completely mystified as to how the sperm are able to make both the differentiation and follow-up action, but no doubt they are eagerly striving to understand these things (I know I would be).  The closest they’ve got thus far is to suggest that it may be a simple genetic mechanism of some kind (as in the case of similarly selective cooperations seen in some social amoeba).

And: I included the picture below, again of a deer mouse, because I think it’s an hilariously fantastic example of the evil eye…

deer mouse 2Credit: Phil Myers (photographer, copyright holder), Museum of Zoology, University of Michigan.  More info here and here.  (I tried to find a picture of sperm in question, but nothing seemed to be (c)-free)

Reference:
Fisher, H., & Hoekstra, H. (2010). Competition drives cooperation among closely related sperm of deer mice Nature DOI: 10.1038/nature08736


ResearchBlogging.org

Stonehenge built as ancient memory storage device? aimee whitcroft Jan 21

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Stonehenge is something of an enduring mystery.  We’ve been fascinated by the how and why of it, and both dimensions have seen their fair share of possible explanations.

stonehenge

For an interesting explanation of how, have a look here: I remember seeing this on the Discovery channel a few years back, and being struck at how much simpler it was than some of the other explanations I’ve heard over the years.

As for why?  Well, people have posited a number of things: astronomy/observatory, prediction, or a site for worship and rituals?   Now, however, a doctoral researcher from La Trobe university in Australia reckons that she might have an answer.

And it’s sciencey! (But still involves rituals and a little observation)

Presenting at the inaugural Marshall McLuhan* Lecture at the National Communications Association convention last year, she put forth her hypothesis that the ‘henge encoded the formal knowledge that the oral culture of the time needed to retain as they developed.  This meant that they didn’t have to move around between different sacred places meaning different things – the ‘henge allowed them a sort of mnemonic (chants and rituals) ‘one monument fits all’-based approach over as they moved from hunter-gatherers to agriculturalists.

A quote:

“When people settle in one place, solstices can be observed.  So the monument was aligned, 500 years into its use, with the winter and summer solstices  to better retain the calendar for both resource management and the ceremonial cycle”

Kelly’s been studying oral cultures all over the world, and looking at how they encode and pass on knowledge, and as seen parallels between them and the ‘henge.

* Marshall McLuhan, for those unfamiliar with him, is seen as the father of modern communications theory.  Copywriters worship him.  Wired magazine named him their patron saint for a while.  Etc.  I strongly recommend the reading of his work…

On the matter of time, and how the past crystallises out of the future aimee whitcroft Jan 20

2 Comments

Yes, you read the title correctly.

u block sml

In a fascinating paper written by George Ellis, of me ol’ alma mater the University of Cape Town and Tony Rothman, from Princeton University in New Jersey, they posit that the place where this crystallisation occurs is, interestingly, the present. Not as in gift (although the present is a gift, yes), but as in the now.  This moment. No, this one. Kinda (but on to that later).

But wait – this sounds a little bit like that whole ‘yes, time technically has no meaning in relative physics, but try saying that to the real world’ issue.  Or maybe that’s just me.

Apparently, cosmologists can, being the amazingly abstract people they are, think of the universe as a sort of block in which space and time are merged.  A static block in which, as the paper says:

“…Time does not ‘roll on’ in this picture. All past and future times are equally present, and the present ‘now’ is just one of an infinite number.”

Confused so far?  Excellent, so was I.  But wait, dear readers, there is more.

Up until now, this blockheaded (sorry) approach hasn’t yielded much of use, but now!  Ah! Something useful – or at least very interesting, which in this area is enough, I think – has come of it.

Our two eminent scientists have developed a new sort of block universe, one into which they’ve introduced the mind-shattering madness that is quantum mechanics.   That wonderful state in which things can be in two places at once, or pop in and out of existence, or be connected across vast distances in such a way that what affects one, affects the other, instantly.  That state.  And they’ve found something interesting.

Firstly, it tends to make the block rather less static. Time does have significance now.  And when one does this, it seems that the future is driven by quantum, and the past by relativity, with the present sitting, as expected, inbetween. For some reason, I keep having in my mind the potentiality of a good or bad cup of coffee, the present experience of a mediocre cup of coffee, and the dried grounds (wormfood) thereafter as my mental image of it.

crystallising block universeThe third graph in the paper, the block universes here take into account quantum mechanics, and show that small pockets of potentiality* can remain even when most of it has stabilised into the present (the wavy lines).  In this way, time acts something like a mixture which is crystallising – the process isn’t entirely uniform.

They also propose that this model may offer a solution for the unidirectional nature of time as we experience it – often called the ‘arrow of time’.  Apparently, it’s because the future does not, in actual fact, really exist yet (yes, yes, I know, but still)…

“One can be influenced at the present time from many causes lying in our past, as they have already taken place and their influence can thereafter be felt.  One cannot be influenced by causes coming from the future, for they have not yet come into being.”

The arxiv blog is of the opinion that the model needs a bit more work (and, of course, some testable predictions would also be super) – I’m simply of the opinion that it’s a really fun idea.

And, as usual, I’m extremely grateful to the arxiv blog for their immensely useful cribnotes.

Finally…

I contacted George Ellis in early December about the paper, and here’s the quotation he kindly provided for me.  Let’s hope that the above explanation makes this a little easier to understand :) Thanks, Prof Ellis!

“Our paper looks at the idea that, contrary to what many physicists claim,  time really matters: time is not an illusion, things really do take place! But in looking at this, one has to fully take into account `quantum weirdness’ as evidenced by many experiments, and in particular by Wheeler’s delayed choice experiments.

“This leads us to the idea of a Crystallizing Block Universe: a space time which `grows’ as time evolves, but does so in such a way that one can still to a small degree influence the `past’, as in those quantum experiments.  Thus spacetime is like a Crystallizing material, where the transition from the uncertainty of the future to the certainty of the past (Quantum weirdness changes to classical certainty) takes place almost everywhere at a time we can call “the present’, but with small remnants of uncertainty remaining that crystallize out later.”

*Basically, the process isn’t completely uniform or simultaneous – apparently, say the authors:

“Quantum physics appears to allow some degree of influence of the present on the past, as indicated by such effects as Wheeler’s delayed choice experiments and Scully’s quantum eraser.”

Introducing a new blogger: Journeys to the Ice aimee whitcroft Jan 19

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To celebrate the start of a brand new year, Sciblogs is pleased to provide all of you with a brand new blogger.

Banner Final New

Matt Wood, of Journeys to the Ice, is going to be blogging about Antarctica and Antarctic science.  Having spent some time actually working in Antarctica with the ARC, it’s a subject close to his (now no doubt thawed) heart.

He also has a podcast, to which anyone can subscribe free, available through iTunes.  It too is called Journeys to the Ice, just to prevent any confusion – have a listen, and we hope you enjoy it!

Welcome, Matt!

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