Three articles of scientific import for the first month of the new year. The first one is about stem cells. Nothing really exciting except that it demonstrates, if in a rather grisly manner, how magically effective they work at staving off the effects of aging. The second one is about liquid diamond on the planets Uranus and Neptune. The last one is about a new theory on how human brains understand music and why we find it appealing.

Stem cells are old news by now but this article from Harvard Magazine describes a simple experiment that nonetheless successfully demonstrates the regenerative powers of stem cells in a very dramatic fashion. The experiment, led by Amy Wagers of Harvard University, surgically joined two mice so that their blood supply became shared. One of the animals was old. The other was young. The idea was that the blood from the young mouse would awaken the stem cells of the old mouse and enhance its regenerative abilities.

Incredibly, the process worked. Muscular damage in the old mouse healed rapidly and new muscle formed almost as quickly as in a young mouse. The experiment also showed that this effect did not diminish the healing ability of the young mouse. As a control, two old mice were also surgically joined in the same manner, but did not exhibit the increased healing ability. What exactly it is in the blood of the young mouse that causes the effect is a still a mystery but that is surely going to be the subject of many new experiments. I just feel sorry for the poor mice.

The second article is from Discovery News and covers research on the melting point of diamond published in Nature Physics. It is based on experiments led by J.H. Eggert of Lawrence Livermore National Laboratory to determine the precise melting point of diamond. This is more difficult than it seems because the team had to melt the diamond while preventing it from transforming into graphite. This was done by taking a clear, natural diamond and blasting it with lasers at ultra-high pressures, liquefying it. The scientists then slowly reduced the temperature and the pressure until chunks of solid diamond appeared again.

What’s interesting about this experiment is that when parts of the diamond solidified, the chunks floated in the liquid diamond instead of sinking, behaving like ice floating in water. This is strange because the solid form of most matter are usually more dense than the liquid form, water being the most common exception. This discovery also fits with a pre-existing theory that there are oceans of liquid diamond on Uranus and Neptune, explaining the lack of alignment between the magnetic poles and the geographic poles of the planets. This would be caused by the liquid diamond deflecting or tilting the magnetic fields of the planets. Of course, it also demonstrates just how common a substance diamond really is.

Finally the last article about how humans perceive and understand music is from the science blog Frontal Cortex. This theory comes from scientists at the University of London and proposes that when we listen to music, our brain develops a prediction of its pattern over time. This means that listening to different genres or styles of music are different skills that can be acquired. However, the pleasure that comes from listening to music is based on the musical piece’s ability to conform to a given pattern and yet unexpectedly deviate from it at key points.

In an experiment, the scientists measured the brain waves of twenty subjects while they were listening to music. They found that unexpected notes, pitches in the music that violated the previously established pattern, generated a spike in brain activity in the subjects. The article explains that since humans learn things by association, music hijacks this mechanism by toying with our associations. If the music conformed always with the expected pattern, then it would be boring. By playing with the pattern in unexpected ways, composers can tease listeners who naturally yearn for a completion of the pattern. This creates tension but gives the listener immense satisfaction when the pattern, after much twisting and turning, is finally completed, just as it is pleasurable to arrive at the solution of a challenging puzzle.