I have seen many interesting sciencey things this week. Which makes sense, given that a large part of my job is to track new research. Sadly, and for the sake of brevity, I’ve had to pick but two for this post.
Starving to stay awake?
Another interesting factoid related to, well, taking in less calories than one might need. It’s already been shown that calorie restriction lengthens lives. Admittedly, this has yet to be proven in humans, but I can’t help thinking of all those Asian centenarians who have lived on a simple diet of rice and whatnot for, well, over a century. Now, something new!
We all know that being tired results in, well, cognitive impairment. A failure to, shall we say, be operating on all six cylinders, including learning impairment. However, scientists playing with fruit flies (as they are wont to do) have discovered something interesting: flies who were starved remained awake but didn’t appear to suffer the negative consequences of this wakefulness. Looking at two different lines of flies, they found that those who have genes meaning they have excess fat were resistant to starvation (and hence this effect), whereas those who were naturally lean, weren’t (and hence got the benefits).
What this shows? That lipid (fats) metabolism, sleep and starvation seem to be intricately intertwined, and further, that lipid metabolism may play an important part in the ability to recover from sleep deprivation, as well as protecting against some of the impairments which can result. Which could help explain why people who suffer routine sleep deprivation tend to be, um larger (also, men: beware! sleep deprivation could kill ya).
What might be a reason? Well, we’re not sure, but it could be that the body reckons that finding food is more important than sleeping. Which makes sense, I guess :)
One question, though - do flies get hyperglycaemic? ‘Cause I know I get shaky, and then ok, and then completely homicidal* when it happens.
Li-ion LCA
In other news, those clever white-jacketed** peeps we call scientists have done the first lifecycle analysis (LCA) on a lithium-ion (Li-ion) battery such as one would use in an electric car. Li-ion batteries are great - they’re basically maintenance-free, lighter, and can store more energy than other batteries (including NiMH batteries). Also, they don’t lose capacity if you keep recharging them from a less-than-full state (unlike, sigh, many other batteries), live for ages, and don’t self-discharge much. So we likes em.
Why an LCA?? First, a word on what an LCA is. Basically, it’s the assessment of any given product from the moment it becomes a glint in a manufacturer’s eye, to the moment it ends up being dumped/recycled. The purpose is measure exactly how much energy and resources go into making said product, and include not only the making of the product itself, but also the energy/resource costs of all its components, and also its eventual dumping/destruction/recycling.
The worry with electric cars is that the environmental impact of actually _producing_ Li-ion batteries might outweigh any environmental benefits conferred by using electric rather than petroleum-engined cars. This, it turns out, is not the case. Indeed, such a battery accounts for at most 15% of the total environmental burden of an electric car, of which a little over half comes from the refinement and processing of its raw materials.
What _does_ matter, however, is the source of the electricity which powers our little electric environment-saver. Assuming that the electricity comes from the mix of coal, nuclear and hydroelectric power sources which is usual in Europe***, an electric car beats a conventional one only if said conventional car is less efficient than 3-4 litres per 100km (70mpg). The electric car’s goodness worsens by another 13% if only coal-powered electricity, but (and this is awesome for NZ), the figures improves by 40% if only hydroelectric (or, one can assume, another sustainable energy) is used. Hooray!
In short, basically, electric cars are only as good as their electricity source. Of course.
In electric cars, environmental impact depends on fuel source - For the first time, researchers have conducted a life cycle analysis on an electric car being run by a lithium-ion battery, and found that it isn’t the battery itself which forms the major environmental burden. Rather, it’s the source from which the electricity generated came. In order for any petrol car to be as environmentally friendly as an electric car (with an Li-Ion battery and powered by a typical European electricity mix), it can must consume 3-4 litres per 100 km. Published in Environmental Science and Technology.
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* Apparently, precipitous blood sugar level drop is particularly prevalent in females. With attendant homicidal leanings (seriously, I’ve scared sandwich people badly). So lads, feed yer hungry ladies!
** Yes, I know that’s generally not the case anymore. Nor are they generally strait-jacketed, either :)
*** This mix of fuel sources makes three times as much pollution as the battery’s entire lifecycle
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Links:
One of the many articles on links between sleep deprivation and obesity
How sleep deprivation can kill ya (boys)
Calorie restriction benefits
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References:
Matthew S. Thimgan, Yasuko Suzuki, Laurent Seugnet, Laura Gottschalk, Paul J. Shaw (2010). The Perilipin Homologue, Lipid Storage Droplet 2, Regulates Sleep Homeostasis and Prevents Learning Impairments Following Sleep Loss PLoS Biology : 10.1371/journal.pbio.1000466
Notter DA, Gauch M, Widmer R, Wäger P, Stamp A, Zah R, & Althaus HJ (2010). Contribution of li-ion batteries to the environmental impact of electric vehicles. Environmental science & technology, 44 (17), 6550-6 PMID: 20695466