Archive | January, 2012

An artificial uterus for sharks, and in-utero cannibalism

20 Jan

Sharks give birth to live young. The eggs “hatch” within the mother’s uterus and stay there for almost a year. Scientists have successfully grown and given birth to baby sharks using an artificial uterus. It is basically a complex aquarium, with multiple chambers, filtration systems for bacteria, water exchange systems, and lots of sensors.

Though the artificial uterus is basically to prove a concept at this point, scientists are thinking that it may one day help to increase the dwindling numbers of the grey nurse shark.

More info here.

Though the idea of an artificial uterus is a bit freaky in a Brave New World kind of way, the thing that blows my mind the most about this is just a fact about sharks I learned along the way. Apparently, grey nurse sharks cannibalize their brothers and sisters while still in the womb. There are many eggs that hatch in utero. Their egg sacks run out after about two months. Hungry, the baby sharks survive the rest of the year in utero by eating their brothers and sisters. In the end, only the biggest and strongest shark remains. As if sharks weren’t scary enough.

Advertisements

A laser that likes a good shake

13 Jan

In general, lasers are not like old television sets: a good whack does not make a laser miraculously work better. Lasers (at least big lasers) take a lot of careful alignment to get working, so whacking, shaking, and leaning on are all out of the question. If you are being trained in a new lab, you will probably hear a lot of “no-touchy” around the laser mountings.

Some scientists in Russia, however, have created a laser that likes a good shake. The laser works by using mirrors to direct light at quantum dots, causing them to emit. The problem is that the quantum dots aren’t always in the state you need them to be in to emit light of the correct wavelength. This is where the shaking comes in. Scientists found that if they exposed quantum dots to sound waves, the properties of the dots shifted in a way that caused them to spend more time in the state that emitted at the correct wavelength. Quantum dots are perfect for this, as their electrons are willing to hang out in an excited state long enough for the sound waves to affect their properties before emitting a photon. The laser with the sound waves had a power 200 times better than without, which is pretty huge. Cool.

Article here.

Still curious? Here’s a bit more info about quantum dots: Quantum dots are tiny bits of matter with special properties. First you need to know about excitons. Excitons are basically an electron and the hole where that electron wants to go, together in a bound state. They are electrically neutral quasi-particles that exist in insulators and semiconductors. Quantum dots’ excitons are confined in all spatial dimensions. The result is a tiny bit of matter that acts (electrically) a bit like a bulk semiconductor and a bit like a single particle. Quantum dots are being researched all over the scientific world nowadays, from lasers and solar cells to quantum computing.

Earth-like planet a result of a gas giant getting swallowed?

12 Jan

Some interesting questions have been brought up by these recent Kepler discoveries. Stars like our sun usually expand to become red giants and then become compact again as helium fusion begins in their cores. Sometimes, the hydrogen is stripped off of the star (by another star for example), leaving just the helium-fusing core behind, compact and very hot. A star in this state has been observed (a hot B subdwarf), where the hydrogen was stripped off, except there is no companion star to have taken the hydrogen away. It’s a cosmic mystery: What happened to the hydrogen?

This star system has several recently-discovered small, (presumed) rocky planets orbiting it. The emerging theory is that when the star expanded to become a red giant, it consumed several gas giants with orbits close enough to be swallowed. When the star contracted again to enter the helium fusion phase, the planets reemerged as small, rocky planets, stripped of their gaseous exteriors. The disruption resulting from the planetary collisions with the star could have stripped the star of some of its hydrogen, causing it to be in the state we now find it: very hot, with several small, rocky planets locked in a tight orbit. Time will tell if this theory is correct. There is so much we don’t understand about the birth and evolution of stars and planets.

Article here.

More earth-sized planets discovered

11 Jan

Scientists have spotted 2 earth-sized planets in an extremely tight orbit around a star very like our own sun.

Article here.

First habitable-zone planet discovered

3 Jan

Observing planets outside our solar system has always been a challenge. The only way to spot one is when a planet crosses in front of its star and causes a fluctuation in the light emitted from that star. Such small fluctuations are difficult to observe from earth, where conditions have to be just right and atmospheric effects accounted for. In the past, we have been able to spot mostly large, Jupiter-sized planets. So, in 2009, NASA launched the Kepler spacecraft, whose only purpose is to observe planets outside our solar system from space, free from atmospheric troubles.

The data are flowing back fast. In fact there have been over 200 earth-sized planets spotted that are waiting to be confirmed by earth-based telescopes before announced. Forty-eight of the planetary candidates lie in the “habitable zone” of their solar systems, which means that the temperatures are right for liquid water to be sustained on the surface. That doesn’t mean they do have liquid water; it just means that it is a possibility. We are waiting on the ground telescopes to confirm these planetary candidates. And then we can get to work on determining their densities, and therefore what they’re made of.

Kepler 22-B is the first confirmed habitable-zone planet discovered outside our solar system. It is on the inside of the habitable zone. Were it in our solar system, it would be somewhere between Earth and Venus.

You may remember the discovery of a planet closely orbiting a double-sun (Kepler 16-B), confirmed by ground telescopes in Septemberish of 2011. Stay tuned for more exciting planetary discoveries from Kepler (there were several exciting ones over Christmas break).