“World’s First Cloned Human Embryonic Stem Cells”

From New Scientist: For the first time, scientists have successfully put human adult somatic cell DNA into an unfertilized egg, induced that egg to divide and develop into a blastocyst – a first step towards a fetus – and harvested embryonic stem cells from those blastocysts, containing the adult’s DNA. There was a problem though: they could only accomplish this if they left in the egg’s DNA, so the stem cells have too many chromosomes (humans have 46; these cells have 69). Nevertheless, it’s a first step towards having real embryonic stem cells (as opposed to IPS cells) with adult DNA, which is a big boon for medical research.

If the above didn’t quite make sense to you, here’s some background:

Stem Cells To Date

You may have heard that there are two main types of “stem cells” in play in the research world: firstly, there are embryonic stem cells, which are cells derived from embryos that can potentially differentiate into any type of body cell. As they divide, their daughter cells will have more and more specific functions and more restricted potential, until they give rise to very specific cell types – a particular type of neuron, or a particular type of blood cell, for example. These cells will have varying limitations; for example, a neuron can’t divide – that’s about as limited as a cell can get. An embryonic stem cell has the most potential of any cell type – it can divide into anything. 

This is useful because it means researchers can grow any kind of cell they want in the lab. They can study how everything develops, and they can study, well, anything. There’s also the potential for stem cell therapy – injecting young, healthy cells into an injury to replace injured cells that the body wouldn’t normally be able to – like neurons, which I mentioned above can’t replicate. 

More recently scientists created induced pluripotent stem cells, or IPS cells. Basically they figured out ways of dedifferentiating adult, specialized cells, making them less specialized, less limited. This meant that they could make embryonic stem cell-like cells that would have the DNA of a particular person. In relation to the uses of stem cells mentioned above, this offers the benefits that you can study the progression of a particular disease, for instance; you could take cells from an adult with a known disease, grow their IPS cells in a lab and see where they go wrong, to put it broadly. In terms of stem cell therapy, you could have better odds of injecting cells into a person without having their immune system reject these cells, since they’d be their own body’s cells.

Perhaps most importantly to a lot of people, you can create IPS cells without destroying human blastocysts in the process, which has been and still is a huge source of political controversy regarding embryonic stem cell research. Contrary to what many morality-based advocates of IPS cell research would have you believe though, IPS cells are not the same as embryonic stem cells. They may be very similar and behave in largely the same way, but they are most certainly not the same thing, and there’s no way to possibly prove that they’re exactly the same, even if it were likely. There’s a lasting place for both of them in research; both will prove useful in understanding everything about human life. 

New Stem Cells

Whew, okay. That’s a very, very brief and simplified overview of stem cells-to-date. This new research took a different approach (typically used in cloning): they took the DNA from an adult, specialized cell, and put it into an egg; they then grew that egg into a blastocyst. From the blastocyst, they could extract embryonic stem cells. This method has the benefits of harvesting actual embryonic stem cells, while also having cells with the DNA of a particular adult, meaning they could be used for specialized stem cell therapy and whatnot. 

But not yet. They weren’t able to get the egg to form a blastocyst when they tried to remove the egg’s own DNA; they had to leave it in there for it to develop into stem cells, meaning that with the egg’s DNA and the adult donor DNA, these stem cells had too many chromosomes – they’re not an accurate model of human cells. Of course, now they’re working on figuring out how to get the egg to develop after they take out its DNA; I’m sure we’ll hear about this in the near future, and it’ll be big news.

Once they can make a viable blastocyst with just the adult DNA, it’s not a far leap to actual human cloning: they just have to implant it into a woman and bring it to term. Of course that entails who-knows-how-many years of troubleshooting, but it’s closer now than it’s ever been before. I call dibs on being cloned. 

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Invisibility Using Carbon Nanotubes: Creating a Mirage

This is very cool: researchers have achieved pretty convincing invisibility in a completely different way from the antimagnet I discussed earlier, by creating a mirage using carbon nanotubes. 

Here’s a video of those nanotubes in action, posted by the Institute of Physics and found via Wired:

 

If you’re curious as to how this works – and don’t even pretend like you’re not – I’ll explain the phenomenon, but I have to take a few steps back (or you can skip the next two paragraphs if you’re comfortable with refraction and mirages):

Every medium, like a gas or liquid, has an index of refraction, meaning the speed of light traveling through that medium. It’s called an index of refraction (or refractive index) because when light changes speed – when it hits the border of two media with different refractive indices – it refracts, changing direction slightly. This is why, for example, images underwater, when seen from above water, can look distorted – the light refracts when it hits the air-water surface, so it doesn’t come straight from the visible object to your eye like it would if it were just going through air or water.

(Edit: Here’s a One-Minute-Physics video from New Scientist explaining why light changes speed in different media.)

A refractive index depends on the medium but also the temperature of the medium. Hot air has a lower refractive index than cold air, and this is the cause of mirages, in the common oasis-in-the-desert sense. When light from the sky nears the ground, it refracts, bending away from the highest heat (the ground), meaning it bends up towards your eyes. This means that you see blue light coming from the direction of the ground, and since we’re usually safe to assume that light travels in a straight line (otherwise we really couldn’t trust anything we see), our brain interprets it as something blue on the ground – water. 

So how did these University of Dallas researchers use this to create invisibility? Well, carbon nanotubes – one-molecule-thick sheets of carbon rolled into tubes – are apparently very good at transferring heat to the surrounding air. They can be electrically heated, causing the air around them to rapidly heat up – like sunlight heating up sand, which heats up the air above it – and (some) light that approaches them will be refracted away.

Because the nanotubes shed heat so quickly, they can also be turned on and off very quickly – pretty awesome. I don’t know that I’d want to wear a suit of extremely hot carbon, but I’m sure they’ll put it to amazing use somehow; apparently (via New Scientist) they can use this effect for acoustical cloaking, possibly for submarines. 

Gravitational Redshift On a Cosmological Scale Verifies General Theory of Relativity

For the first time, gravitational redshift has been measured outside of the solar system, on a cosmological scale. This effect of gravity on light is predicted by the general theory of relativity, and these measurements from the Dark Cosmology Centre at the Niels Bohr Institute, published in Nature, match the predictions. If you’re familiar with redshift, feel free to skip ahead to the second quote block.

Redshift is the result of the Doppler effect on light. Wikipedia has a pretty solid explanation of the Doppler effect, which is when wave frequencies increase (and thus wavelengths decrease) as the source of the wave moves towards the observer, and vice versa for a source moving away:

When the source of the waves is moving toward the observer, each successive wave crest is emitted from a position closer to the observer than the previous wave. Therefore each wave takes slightly less time to reach the observer than the previous wave. Therefore the time between the arrival of successive wave crests at the observer is reduced, causing an increase in the frequency. While they are traveling, the distance between successive wave fronts is reduced; so the waves “bunch together”. Conversely, if the source of waves is moving away from the observer, each wave is emitted from a position farther from the observer than the previous wave, so the arrival time between successive waves is increased, reducing the frequency. The distance between successive wave fronts is increased, so the waves “spread out”.

Light can be described as a wave, with different wavelengths for different colours. Blue has the smallest wavelength and highest frequency, red has the largest wavelength and smallest frequency. That means that, as described by the Doppler effect, when a source of light (or more generally, electromagnetic radiation) is moving away from an observer it will shift towards the red end of the spectrum. Since the universe is expanding, light from distant galaxies is redshifted, and the degree of redshift can tell you their distance: this is cosmological redshift, or Hubble’s Law.

Meanwhile there is gravitational redshift: light moving from a place of stronger to weaker gravity will be redshifted. To the best of my understanding, this is because time moves slower near stronger sources of gravity, which intuitively seems to make sense as an explanation for wavelength expanding as it moves away from the gravity source. Light also has to travel further when it goes near a large source of gravity, since gravity curves space as well as time.

Gravitational redshift is what’s explained and predicted by general relativity, and what these researchers observed. From Science Daily:

Radek Wojtak, together with colleagues Steen Hansen and Jens Hjorth, has analysed measurements of light from galaxies in approximately 8,000 galaxy clusters. Galaxy clusters are accumulations of thousands of galaxies, held together by their own gravity. This gravity affects the light being sent out into space from the galaxies.

The researchers have studied the galaxies lying in the middle of the galaxy clusters and those lying on the periphery and measured the wavelengths of the light.

“We could measure small differences in the redshift of the galaxies and see that the light from galaxies in the middle of a cluster had to ‘crawl’ out through the gravitational field, while it was easier for the light from the outlying galaxies to emerge,” explains Radek Wojtak.

They also calculated the mass of the galaxy cluster and from that its gravitational potential, and armed with this could reliably predict the redshift from different regions of the cluster. Einstein emerges victorious, yet again – so you can see why everyone is very skeptical about the now famous CERN neutrino experiment

In trying to wrap my head around this I discovered this site explaining relativity, time dilation and quantum theory in a pretty digestible form; you should check it out if you have any interest.

“Ten Things Everyone Should Know About Time”

Cosmic Variance has an interesting and brief article about the nature of time – ten realities about time that we may not realize. They’re already brief points so I won’t try to summarize them all (go read it!), but here are some parts I like:

2. The past and future are equally real. … Intuitively we think that the “now” is real, while the past is fixed and in the books, and the future hasn’t yet occurred. But physics teaches us something remarkable: every event in the past and future is implicit in the current moment… As Einstein put it, “It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence.”

4. You live in the past. About 80 milliseconds in the past, to be precise. Use one hand to touch your nose, and the other to touch one of your feet, at exactly the same time. You will experience them as simultaneous acts. But that’s mysterious — clearly it takes more time for the signal to travel up your nerves from your feet to your brain than from your nose. The reconciliation is simple: our conscious experience takes time to assemble, and your brain waits for all the relevant input before it experiences the “now.” Experiments have shown that the lag between things happening and us experiencing them is about 80 milliseconds.

10. A lifespan is a billion heartbeats. … Remarkably, there exist simple scaling laws relating animal metabolism to body mass. Larger animals live longer; but they also metabolize slower, as manifested in slower heart rates. These effects cancel out, so that animals from shrews to blue whales have lifespans with just about equal number of heartbeats — about one and a half billion, if you simply must be precise. In that very real sense, all animal species experience “the same amount of time.”

Obviously these are imperfect points by virtue of being extremely simplified, but they’re pretty interesting nonetheless. I find the “you live in the past point” particularly interesting. Reality is changing faster than we can perceive it; everything you think you see is wrong (in that your perception does not match your body’s current state, albeit only by 80 milliseconds). Keanu “whoa”. 

The Coriolis Effect In Brief

Bad Astronomy has a great, short explanation of the Coriolis Effect (at least I assume it’s great; it now comprises 100% of what I know about the Coriolis Effect). You should click over and read it, but if you’re really too lazy then I’ll take the challenge of trying to make the explanation even shorter; be forewarned that it’ll be only slightly shorter but much less goodtastic. 

The Earth rotates. Different parts of the Earth rotate at different speeds; the equator rotates the fastest, the poles don’t rotate at all (I hope that’s intuitive). Say there’s a weather system at the equator; it’s rotating eastwards at max speed (but it’s stationary relative to the also-rotating-eastwards equator). If it moves away from the equator (north or south), suddenly its speed is faster than the rotation of the earth at that latitude, so it’s going to be moving east.

If a weather system is near the poles it’ll be rotating very slowly; now if it moves towards the equator, it’ll be going slower than the rotation of the Earth at that latitude, so it’ll start traveling west. 

So if air is rushing into an area north and south, it’s going to end up rotating. If it’s in the northern hemisphere, the northbound air will loop east, the southbound air will loop west, forming a counterclockwise rotation, and the opposite in the southern hemisphere.

And that is why hurricanes rotate in those directions. Makes almost too much sense… 

Radiocarbon Dating

By request, I shall use my expertise to explain the magic that is carbon dating – what allows archaeologists to deduce the age of ancient artifacts.

Just kidding, I’ll link you to someone better: How Stuff Works has a 1 minute video that explains it pretty concisely. I wish I could embed it here, but WordPress is a jerk like that.

If for some reason that video didn’t do the subject justice for you, here’s the deal, in some more detail: Read more of this post

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