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A surprisingly compact early galaxy

Sunday, October 25, 2009

Astronomers are beginning to learn significant details of the structure of galaxies in the early universe. And what they're learning is rather surprising: at least some early galaxies are almost as massive as otherwise similar galaxies in the present universe, yet they are much smaller in linear size, by a factor of five, thus much more compact.

What time period are we talking about here? It's not actually the time that the earliest galaxies formed, which was less than a billion years after the big bang. Instead, the time in question was around 3 billion years after the big bang.

Although that's roughly 10.7 billion years ago, many galaxies at that time were actually fairly mature, even old. This is because they had been around for more than 2 billion years, which is more than time enough for all their massive, hot, bright stars to have burned out long before. If these galaxies had depleted most of their star-forming material, not many new, hot, young stars could form. The rate of star formation might be as small as it is now in the Milky Way, only two to four solar masses worth per year, compared to thousands per year at the peak.

Young stars include proportionately more massive stars, because it's the massive ones that burn out quickly. Stars that are more than 2 billion years old have to be smaller. Smaller stars are also dimmer, cooler, and redder in color. (Recall the Hertzsprung–Russell diagram, which displays the relationship between luminosity and color.) Consequently, older galaxies that are no longer forming many new stars are also redder, and that's how astronomers estimate roughly galaxy age, or at least the length of time since rapid star formation ceased.

Certain events, such as collisions and mergers between galaxies can fire up rapid star formation again. So the correlation between color and age is not at all exact, but it's still there.

Another fact about galactic appearance is that the central part of any galaxy, even a spiral, is much brighter than the outer reaches, like the spiral arms (if any), simply because the central part of a galaxy contains most of the stars. So at the distances we're concerned with here – over 10 billion light-years – all we can really observe with existing optical telescopes is the central part of a galaxy. To a first approximation, then, very distant galaxies look ellipsoidal in shape, even if they're really spirals.

For the time period we're interested in, 3 billion years after the big bang, the redshift of light we see from objects at that time (denoted by z) is about 2.2. (See here for a fuller explanation.) The definition of redshift means that the wavelength of light emitted at z~2.2 is stretched by a factor of z+1~3.2. So visible light, with a wavelength of about 400 to 700 nanometers is shifted to 1.3 to 2.2 microns, in the near infrared. Although this kind of infrared light can be studied by ground-based spectroscopy, the best optical imagery has to be done from space-based instruments, which makes the job a lot harder.

With all that as background, the newly published result we're concerned with is really pretty simple. It has confirmed that a certain galaxy, named 1255-0, at z=2.186 is about a third as massive (~2×1011M) as the Milky Way and similar galaxies in our neighborhood at the present time, even though its central region is much smaller, with a radius of about 2500 light years. Consequently, stars in the central region of 1255-0 are packed much more closely together.

This observation raises two distinct problems: First, most existing models of galaxy formation do not predict that typical galaxies of that age will be so compact. Second, no galaxies of that sort seem to exist in our general neighborhood, so at least some of them presumably evolved from galaxies like 1255-0 – and it's not clear how that could happen.

Here's the research abstract:

A high stellar velocity dispersion for a compact massive galaxy at redshift z = 2.186
Recent studies have found that the oldest and most luminous galaxies in the early Universe are surprisingly compact, having stellar masses similar to present-day elliptical galaxies but much smaller sizes. This finding has attracted considerable attention, as it suggests that massive galaxies have grown in size by a factor of about five over the past ten billion years (10 Gyr). A key test of these results is a determination of the stellar kinematics of one of the compact galaxies: if the sizes of these objects are as extreme as has been claimed, their stars are expected to have much higher velocities than those in present-day galaxies of the same mass. Here we report a measurement of the stellar velocity dispersion of a massive compact galaxy at redshift z = 2.186, corresponding to a look-back time of 10.7 Gyr.

Note that the research isn't the first to identify very massive but compact galaxies at z~2. Rather, it's new in that it has confirmed the estimate of mass by a new method, and that's what's significant.

You see, there are basically two different ways, at present, to estimate the mass of a very distant galaxy. One method relies on a plausible assumption, that stars less than 2 billion years old, except for the very youngest, have fairly well-known distributions of mass and luminosity. And so, from the total luminosity of the galaxy that we can observe, we can form a good estimate of the total mass of stars. This is sometimes called the "photometric" mass.

This sort of measurement is what has been used to infer that a number of galaxies at z~2 may have been very massive in spite of being small in extent. As suggested above, this observation raises at least two problems, so astronomers would like to measure mass in a different way, just to be sure. Besides, perhaps the assumptions about the mass and luminosity distributions of the stars in such galaxies could be wrong.

Fortunately, there is another type of observation that can lead to good mass estimates, but it is much more difficult to make. This involves measuring the "dispersion" of velocities of stars in the galaxy. That is related to the distribution of stellar velocities. But since we can't distinguish individual stars at that distance we certainly can't measure their velocities (by very slight differences in stellar redshifts from the redshift of the galaxy as a whole).

Even though the measurement is difficult to make in practice, it's simple to describe. One simply looks at the width of a few absorption lines in the galaxy's spectrum. If the lines are wide, it means that individual stars have substantially different velocities, including a certain proportion which are quite large. This is, basically, the meaning of "dispersion".

From the relative number stars with high velocities one can infer the total mass. This yields what is called the "dynamical" mass of the galaxy. What the present research found is simply that the dynamical mass of 1255-0 is pretty close to the known photometric mass.

Why is it that lots of high-velocity stars indicates a substantial mass? Just fairly basic physics, based on two of Newton's laws. (If you're a physicist, you learned this a long time ago, so it's "obvious".) The first is Newton's law of gravitation, which is F=G×M×m/r2. This describes the gravitational force (F) between two objects having masses M and m separated by a distance r. G is a certain constant called, of course, the gravitational constant. This can be applied to a galaxy with mass M and one of its stars, with mass m, where r is the distance from the star to the center of mass of the galaxy.

The other law is Newton's second law of motion, which says F=ma. F is, again, the gravitational force of the galaxy, m is the mass of a particular star, and a is the acceleration of the star due to the force. (F and a are actually "vector" quantities, of couse, meaning they have a direction in 3-space.) You can think of the acceleration of an object as a way of measuring the force acting on it.

Putting the two laws together, we find that for any particular star its accleration will satisfy a = G×M/r2, so the star's mass doesn't matter at all, only the mass of the galaxy. Just as in our own galaxy, almost all stars are in orbit around the center of mass of the galaxy, so a star's velocity, as seen from far away, varies periodically in a predictable way, deducible from acceleration (which is the rate of change of velocity).

From calculations that are routine (at least for a physicist) one thus obtains a good estimate of the mass of a galaxy from the distribution of velocities of its stars, which in turn is deducible from the dispersion of spectral lines.

There is one additional complication: matter in any form other than what makes up stars, most especially dark matter. But the present research shows that the mass as estimated photometrically (where any nonluminous matter plays no part) and the mass as estimated dynamically (where dark matter could be important) are pretty close.

Consequently, there isn't much nonluminous matter (including nonbaryonic dark matter) in the central part of the galaxy where most of the stars are. This is as expected, since most galaxy models as well as observations have the dark matter distributed over a much larger volume than the central part of the galaxy. (Other elementary physics shows that matter outside the orbit of a star does not affect the star's motion, as long as that matter is evenly distributed.)

The net of all this is that the two problems mentioned above are real and pose questions that need to be answered.

How could massive galaxies as compact as 1255-0 have formed in the first place? It is not the case that massive compact galaxies like 1255-0 are exceptional anomalies at z~2. Instead, they seem to make up as much as 30 to 40% of galaxies whose masses have been estimated (photometrically) at that distance.

Existing models involving cold dark matter mostly do not predict such a thing. But this doesn't mean that the models can't be refined. In particular, the whole theory of cold dark matter as a driver of galaxy formation need not be discarded. It isn't necessary to invoke some exotic new physics or variations of Einstein's general relativity. The most natural approach is to find a suitable refinement of the galaxy formation model. There is research that was reported in January 2009 and offers one sort of model. It involves filaments of dark matter that conduct streams of cold gas into a central region around which a galaxy grows. Research paper: here. Additional stories: here, here, here, here.

The other problem has received less attention. The difficulty is in explaining how a galaxy (or rather, its central region) grows by a linear factor of five or so over a period of ~10 billion years, even though the mass contained in that region doesn't grow much at all. It just seems to "puff up".

Galaxies have long been presumed to grow through mergers of less massive galaxies, the most important of which are of roughly equal mass. One possibility is that few such mergers actually occur, and instead colliding galaxies mostly pass through each other without merging, but with some expansion of linear size each time. Another possibility is that there are many mergers involving mostly low-mass galaxies captured by much larger ones. That would also help explain another major puzzle: why many fewer low-mass galaxies are observed than current models predict.

Questions of this sort are not easy to resolve. They're a lot like questions about the evolution of life. All we can actually observe consists of snapshots from different points of time. Events unfold too slowly to actually see what happens. And moreover, the very small galaxies that might play a role are currently too faint to observe over most of the past 12 billion or so years of cosmic history.

van Dokkum, P., Kriek, M., & Franx, M. (2009). A high stellar velocity dispersion for a compact massive galaxy at redshift z = 2.186 Nature, 460 (7256), 717-719 DOI: 10.1038/nature08220

Further reading:

Astronomers Find Hyperactive Galaxies in the Early Universe (8/5/09) – press release

Speeding Stars Confirm Bizarre Nature of Faraway Galaxies (8/5/09) – article at space.com

Galactic evolution: more data, no more answers (8/12/09) – article at arstechnica.com

Galaxy formation: Too small to ignore (8/6/09) – Nature news article

Puffing up elliptical galaxies (10/3/09) – blog post (SarahAskew)

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NGC 4945: The Milky Way’s not-so-distant Cousin

Thursday, October 15, 2009

NGC 4945: The Milky Way’s not-so-distant Cousin (9/2/09)
ESO has released a striking new image of a nearby galaxy that many astronomers think closely resembles our own Milky Way. Though the galaxy is seen edge-on, observations of NGC 4945 suggest that this hive of stars is a spiral galaxy much like our own, with swirling, luminous arms and a bar-shaped central region. These resemblances aside, NGC 4945 has a brighter centre that likely harbours a supermassive black hole, which is devouring reams of matter and blasting energy out into space. ...

Scientists classify NGC 4945 as a Seyfert galaxy after the American astronomer Carl K. Seyfert, who wrote a study in 1943 describing the odd light signatures emanating from some galactic cores. Since then, astronomers have come to suspect that supermassive black holes cause the turmoil in the centre of Seyfert galaxies. Black holes gravitationally draw gas and dust into them, accelerating and heating this attracted matter until it emits high-energy radiation, including X-rays and ultraviolet light.

NGC 4945 – click for 1280×1280 image

More: here

Telomerase and Wnt signaling

Saturday, October 10, 2009

Now that research into telomeres and telomerase has (finally) garnered a Nobel Prize, it's a good time to write about recent research on the subject.

Seminal work on telomeres by Elizabeth Blackburn, one of the Nobel winners, was published way back in 1978, and active studies have been going on ever since. So perhaps it's not surprising that the rate of new findings is not so rapid as occurs in newer areas – such as stem cells.

But fascinating new results on telomeres and telomerase do still appear, and one of them connects with more recent research areas – such as Wnt signaling and... stem cells.

Here's the press release:

Discovery pinpoints new connection between cancer cells, stem cells (7/1/09)
A molecule called telomerase, best known for enabling unlimited cell division of stem cells and cancer cells, has a surprising additional role in the expression of genes in an important stem cell regulatory pathway, say researchers at the Stanford University School of Medicine. The unexpected finding may lead to new anticancer therapies and a greater understanding of how adult and embryonic stem cells divide and specialize.

Don't bother getting excited about the "new anticancer therapies" bit. That's just boilerplate that about 77.3% of all press releases dealing with cell biology contain, presumably to impress the rubes. If you need something to get excited about, you might recall that telomerase is also being investigated intensively in connection with issues of aging and longevity, independently from cancer. However, while it's possible that something of medical significance may come from this research, that's probably way down the road.

Before discussing the new research, let's review some of the background on telomeres, telomerase, and Wnt signaling.

To begin with, a telomere is a series of short repeated segments of DNA found at the ends of chromosomes in all eukaryotic cells. In cells of vertebrate animals the repeated segment is TTAGGG (where the letters represent nucleobases: T=thymine, A=adenine, G=guanine).

The total number of nucleotides in these repeated segments varies a great deal from species to species, but in humans it is (initially) about 10,000 nucleotides (or ~1700 complete segments). I say "initially", because part of the telomere is lost every time a cell divides – perhaps 50 to 200 nucleotides per division. Obviously, this means that an adult cell newly derived from a stem cell can divide at most 50-200 times before the telomere is all gone. In practice, the number is a lot less than the maximum, perhaps 40 to 60 times, which is called the Hayflick limit. Cells are programmed to stop dividing on reaching this limit, since otherwise useful DNA would be lost or damaged upon further division.

Why does this loss occur? It seems to be somewhat of an accident of the nitty-gritty details of how DNA replication occurs during cell division. I won't go into that, since it's best explained with some diagrams; you can read about it at Wikipedia. In fact, in the early days of molecular biology (around 1972), what happens at the end of chromosomes during DNA replication was rather puzzling, and the puzzle was called the "end replication problem". Now it's pretty well understood, though somewhat messy.

In any case, the loss of DNA from the telomeres during cell division is a fact, and it conveniently explains the existence of the Hayflick limit, which had been recognized since 1965. What happens when the teleomere is all used up and the limit is reached? Cells that have reached the limit don't necessarily die (though they might), but they do stop dividing, and they enter a static phase of cell life known as senescence.

If you think about it, senescence can be a problem, especially in certain tissues that need to continually replenish their cells, such as skin and the lining of the intestines, as well as hair, fingernails, etc. How is senescence circumvented in such tissues? The answer is (adult) stem cells. It turns out that stem cells are not subject to the Hayflick limit. It's not clear whether they are subject to limits at all.

Like any other cell type, stem cells also divide (by the process technically known as mitosis). But there is one difference from the way "ordinary" cells divide. Stem cells can divide asymmetrically, where one daughter cell is another stem cell, but the other daughter is a "progenitor cell", which is close to a normal, fully-differentiated adult cell of a fixed tissue type. Progenitor cells differentiate further into the final form when they divide, and they are able to divide only a limited number of times.

So how is it that stem cells are able to escape the Hayflick limit, dividing an indefinite number of times, even though they are also subject to the same loss of telomere nucleotides with each division? The answer is the enzyme telomerase, which is able to rebuild shortened teleomeres. It's fortunate for the longevity of complex organisms that telomerase exists, otherwise stem cells would not be able to divide often enough to allow tissues exposed to harsh conditions (such as skin and intestinal lining) to be replenished.

In order to explain the results of the research to be described here we need to say more about telomerase, but first let's summarize the function of telomeres. At first it may seem that all they do is compensate for the sloppy way that DNA replication works, by providing long stretches of expendable DNA at the ends of chromosomes. But there is one other notable function: teleomeres are a useful "cap" at the end of a chromosome that is recognizable to cellular mechanisms responsible for detecting DNA damage. If it weren't for the telomeres, the ends of chromosomes would be indistinguishable from DNA damage, which can result from errors in the replication process, as well as damage due to external agents such as ionizing radiation or harmful chemicals. Cells have various mechanisms for repairing many kinds of damage, but even if repair isn't possible, other mechanisms exist that recognize the damage and prevent further cell division or cause programmed cell death (apoptosis).

Not all DNA damage can be repaired or compensated for by apoptosis or cessation of cell division. Unrepaired DNA damage (however it occurs) is the main cause of cancer (though not the only one). So the existence of the Hayflick limit as a result of teleomere shortening acts as one defense against cancer. Cancer can be defined as the uncontrolled proliferation of cells as a result of DNA damage (affecting existing mechanisms that normally control proliferation) or other causes. So fixed limits on the number of times a cell can divide is one of a number of mechanisms organisms have to guard against cancer.

Before moving on, here's a quick summary of the functions served by telomeres: (1) compensate for the chromosome "end replication problem"; (2) make it possible for cells to distinguish chromosome ends from damaged chromosomes; (3) provide natural limits to the number of times ordinary cells can divide, as protection against cancer.

As noted above, the third of these functions is a problem for stem cells that do need the ability to divide an indefinite number of times. Repair of tissues exposed to harsh conditions is not the only circumstance this ability is needed. Another very important case is that of embryonic development. Multicellular, sexually-reproducing organisms start from a single cell (zygote). Yet there are close to 1014 cells in an adult human.

It is true that a single cell that underwent 47 cycles of cell division could theoretically produce that many cells. But that's really pushing the limits, since some cell types are needed in much larger numbers than others. The bottom line is that embryonic development is the other main circumstance when limits on cell division need to be overcome.

Telomerase is what makes this overcoming of telomere limits possible. And it does it in a pretty straightforward way. Telomerase is a complex molecule with three distinct parts. Two of these are proteins: Telomerase Reverse Transcriptase (TERT) and dyskernin, which are coded for by distinct genes. TERT does most of the work. The other part is a short piece of RNA, called the telomerase RNA component (TERC), which contains and is somewhat longer than the repeat unit (TTAGGG in vertebrates). Like any other reverse transcriptase enzyme (other examples of which occur in RNA viruses such as HIV), TERT simply translates a piece of RNA into DNA and inserts it into a chromosome. In the case of telomerase, the RNA is carried inside the enzyme complex itself. Telomerase does its job simply by replacing the telomere DNA that is lost from chromosomes during mitosis.

So telomerase performs the function of rebuilding telomeres, and this is essential in tissues where cells must proliferate rapidly, such as in embryonic development and tissue regeneration. But as we noted above, if the restriction on cell division is circumvented, the risk of cancer goes up. Although telomerase serves an essential purpose in specialized contexts, it also makes it possible for cells to become cancerous. Consequently, telomerase is not expressed in most adult body cells. However, telomerase is expressed in about 90% of tumor cells.

It might seem as though one approach to controlling or even destroying cancer could involve either inhibiting telomerase or developing a vaccine using telomerase to induce an immune response against telomerase-rich cancer cells. There are in fact various clinical trials exploring both techniques. But this is tricky and rather risky, because as we've observed, telomerase is needed in stem cells required for tissue regneration, at least once the cells have begun proliferating. Those cells need to be protected while they are simply doing their job – replenishing skin and intestinal linings, for example. We need to understand how such cells are controlled so that they work without leading to cancer.

Anyhow, TERT is a protein that is an essential component of telomerase, which plays an important role in cell proliferation. The new research we're finally almost ready to discuss shows that, surprisingly, TERT also plays a role in a completely different aspect of cell proliferation having nothing to do with telomeres. That's where Wnt signaling comes in.

Wnt signaling is a subject we've looked at several times before. Some of the relevant articles are here, here, here, and here. Wnt was first noticed in connection with embryonic development and tissue regeneration. This article has many examples. The name Wnt alludes to a gene called "wingless", because the gene causes fruit flies to lack wings when the gene is mutated.

Recently Wnt's importance in stem cells has also received a lot of attention. Some of our discussion of that may be found here, here, here, and here. Wnt's relevance to cancer and cancer stem cells is often touched on in most of all the articles listed.

Basically, Wnt is the name of a family of proteins that play an important role in signals promoting cell proliferation, especially in the context of embryonic development and tissue renewal (skin, intestines, hair, and immune system cells). Since Wnt proteins promote proliferation, they also play a role in cancer.

The fact, then, that new research shows teleomerase can enhance Wnt signaling is signficant as a second, entirely separate route through which it plays a role in both normal stem cell function and cancer.

Here's the research abstract:

Telomerase modulates Wnt signalling by association with target gene chromatin (7/2/09)
Stem cells are controlled, in part, by genetic pathways frequently dysregulated during human tumorigenesis. Either stimulation of Wnt/β-catenin signalling or overexpression of telomerase is sufficient to activate quiescent epidermal stem cells in vivo, although the mechanisms by which telomerase exerts these effects are not understood. Here we show that telomerase directly modulates Wnt/β-catenin signalling by serving as a cofactor in a β-catenin transcriptional complex. The telomerase protein component TERT (telomerase reverse transcriptase) interacts with BRG1 (also called SMARCA4), a SWI/SNF-related chromatin remodelling protein, and activates Wnt-dependent reporters in cultured cells and in vivo. TERT serves an essential role in formation of the anterior–posterior axis in Xenopus laevis embryos, and this defect in Wnt signalling manifests as homeotic transformations in the vertebrae of Tert-/- mice. Chromatin immunoprecipitation of the endogenous TERT protein from mouse gastrointestinal tract shows that TERT physically occupies gene promoters of Wnt-dependent genes. These data reveal an unanticipated role for telomerase as a transcriptional modulator of the Wnt/β-catenin signalling pathway.

That's a pretty good summary of the paper, but I imagine most people would like a bit more explanation of what's going on.

Previous research had disclosed some interesting "coincidences" involving stems cells and embryonic development, in which both telomerase and Wnt signaling seemed to have similar effects, even though no obvious connection was known. For example, epidermal (skin) stem cells spend most of their time in a quiescent (non-dividing) state. The main function of Wnt proteins is to carry signals between cells that inform target cells of a need to start dividing, for example during various stages of embryonic development or to heal wounds. The curious thing is that telomerase was known to have a similar effect as Wnt signaling on some stem cells. This coincidence is enough to motivate looking for a connection.

If you are really into this sort of thing, you might want to refer to this diagram of various cell signaling pathways, including that of Wnt. One of the things it illustrates is the position of β-catenin in the Wnt pathway. β-catenin operates at the end of the pathway, where it becomes a part of a protein complex that includes transcription factors (known as TCF/LEF), and the complex causes expression of a variety of Wnt-regulated genes, which go on to enable cell proliferation.

One of the main findings of the research is that TERT interacts with another protein called BRG1 (or SMARCA4), and together these become important parts ("cofactors") of the gene-regulating protein complex. It was also determined that TERT is the only component of telomerase that is involved with Wnt signaling.

Apparently TERT is more important for some instances of Wnt signaling than for others. For example, low levels of TERT in embryos of the frog Xenopus laevis resulted in very abnormal development of the frog embryos (in terms for the anterior-posterior axis of the body). But low levels of TERT at a later stage of development caused only somewhat more subtle defects in formation of ribs in the embryo. Similar somewhat minor effects also occured with low levels of TERT in mouse embryos, and these defects were much like the effects of low levels of β-catenin.

So what, then, is so interesting about this research? It's satisfying to know the reasons for what were previously just observed coincidences, such as the fact that telomerase is not only very important for the ability of stem cells to divide freely (during embryonic development and tissue regeneration) but that it also can help stimulate stem cell division.

But what makes this research especially significant is the importance of the biological processes in which both telomerase and Wnt signaling play major roles – namely embryonic development, tissue regeneration and repair, and cancer. The latter two processes are especially important for medical reasons, although we're still a long way from being able to use this knowledge about telomerase and Wnt signaling for therapeutic purposes.

As far as cancer is concerned, we need to understand much more about how telomerase and Wnt signaling work in various types of stem cells, given that stem cells may play a big role in some types of cancer (though not in others).

But tissue regeneration and repair are also of significant medical interest, since it is the eventual inability of various types of tissues to replenish themselves in old age that is responsible for the many debilities that appear in old age. Many people have speculated that telomerase could help alleviate this problem – provided it does not also lead to facilitating the development of cancer.

Finally, we are left with the puzzle of how it is that TERT happens to play important – yet quite distinct – roles in two very separate processes that are, neverthelesss, both important for cell proliferation. We don't know the answer to this, but we can speculate. Perhaps it's because TERT has to be around anyway for stem cells during embryogenesis and tissue regeneration. That being the case, perhaps at some point in evolution, TERT also happened to help boost Wnt signaling a little. The effect of amplifying Wnt signaling in the same contexts that telomerase was needed would be advantageous and worth conserving. This kind of double duty should lead to more efficient use of cell resources.

Park, J., Venteicher, A., Hong, J., Choi, J., Jun, S., Shkreli, M., Chang, W., Meng, Z., Cheung, P., Ji, H., McLaughlin, M., Veenstra, T., Nusse, R., McCrea, P., & Artandi, S. (2009). Telomerase modulates Wnt signalling by association with target gene chromatin Nature, 460 (7251), 66-72 DOI: 10.1038/nature08137

Further reading:

Cell biology: The not-so-odd couple (7/2/09) – expository article in Nature about the telomerase-Wnt research

Nobel in medicine honors discoveries of telomeres and telomerase (10/5/09) – news article in Science News

Nobel for insights into ageing and cancer (10/5/09) – news article in New Scientist

Chromosome protection scoops Nobel (10/5/09) – news article in Nature

Three Americans Win Physiology or Medicine Nobel (10/5/09) – news article at ScienceNOW.com

Work on Telomeres Wins Nobel Prize in Physiology or Medicine for 3 U.S. Genetic Researchers (10/5/09) – news article in Scientific American

Nobel Winners Isolate Protein Behind Immortality, Cancer (10/5/09) – news article at Wired.com


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Wednesday, October 7, 2009

Inventor Demonstrates Humanoid Robot's Latest AI Abilities (8/25/09)
In August 2007, Le Trung invented Aiko, a Yumecom, or "Dream Computer Robot." Although it took only a month and a half to build Aiko's exterior, the artificial intelligence software has been a work in progress ever since. Recently, Le Trung has demonstrated his most recent improvements to the software, called BRAINS (Bio Robot Artificial Intelligence Neural System).


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