The yellow and black “trefoil” is familiar to many of us as a warning symbol for radiation or radioactive materials. It is used internationally and is well-established. Yet there is nothing inherent in the symbol to suggest either radiation or danger, aside perhaps from the yellow color used. If one has not been educated about what the symbol represents, it will be meaningless to him.

The new, supplementary warning symbol. Source: IAEA.

As a result, New Scientist reports, the International Atomic Energy Agency is adding a new symbol to supplement the old one. This symbol incorporates the trefoil, but also shows it leading to a skull and crossbones, signifying death, as well as a person running away. The IAEA’s tests suggest that people could easily understand the danger it was conveying.

At first glance, it appears a bit extreme. This is not a replacement, though. The IAEA states

The symbol is intended for IAEA Category 1, 2 and 3 sources defined as dangerous sources capable of death or serious injury, including food irradiators, teletherapy machines for cancer treatment and industrial radiography units. The symbol is to be placed on the device housing the source, as a warning not to dismantle the device or to get any closer. It will not be visible under normal use, only if someone attempts to disassemble the device. The symbol will not be located on building access doors, transportation packages or containers.

# An Inconvenient Truth wins two Academy Awards

The 79th Academy Awards, popularly known as the Oscars, were awarded today. An Inconvenient Truth, Al Gore’s documentary about global warming, was nominated for best documentary. Melissa Etheridge wrote the excellent and apropos “I Need to Wake Up” for the movie, and it earned a nomination for best original song. Both of them won tonight!

I was not surprised that An Inconvenient Truth won the award for best documentary. It has had a profound impact on the consciousness of the United States—I would expect it to be eventually listed along other nation-changing creative works. Spotting that the Oscars have “gone green” this year was a good hint as well. I admit I did not expect “I Need to Wake Up” to win, however. It’s an outstanding song, but three songs from Dreamgirls were nominated as well. But the song really complements An Inconvenient Truth and expresses the dual feelings of shock and motivation so well. Congratulations to Al Gore, Melissa Etheridge, Lawrence Bender, Laurie David, and Davis Guggenheim!

If you have not yet seen An Inconvenient Truth, please do so. For more information, you may wish to read two previous weblog posts of mine: “Is It Getting Hot in Here?” and “What Are You Going to Do About Global Warming?”.

In other news, as Anarctic ice melts, scientists are able to study organisms that were previously under the ice shelves. While the discovery itself will yield interesting information about these creatures, it unfortunately is part of a trend that will ultimately cause harm (and is causing harm) to life worldwide.

In good news, as part of a buyout of Texas’ largest electric company (TXU Corp.), plans for eight of the eleven proposed coal plants may be scrapped. Combustion of coal is a major contributor to greenhouse gases and global warming.

Update: Think Progress has video clips of the acceptance speech as well as other Al Gore’s other appearances at tonight’s Academy Awards.

# Climate Change Update (22 Feb 2007)

As I mentioned in my previous Update, so many effects of human-induced climate change (that is, global warming) are now appearing in the scientific literature that it is too difficult for me to keep up posting them here; I’ll point out a few that caught my attention.

Carbon dioxide levels continue to rise; this January saw a new record high at 390 parts per million. And according to the U.S. National Oceanic and Atmospheric Administration (NOAA), this past January was the warmest January on record. Of course, global warming refers to changes in climate; it is quite possible that a month or even a year may be cooler than the preceding one; the warming trend is significant over years and decades, however. And fast-moving rivers of water are flowing under West Antarctica’s ice sheet, contributing to rapidly changing lakes; this could have major implications for the stability of the ice.

As we’ve seen, climate change will have (and is having) major impact on Earth’s ecosystems. A new study suggests that a species of turtle would see significant population losses.

But before I go further, I would like to address a common misconception. People sometimes express doubt that we could “destroy the Earth” through global warming or any other such process. The Earth has been through major changes before. And as a Live Science article discusses, they’re right. Life on Earth has created some pretty hefty changes in the past. But the problem is, a significant amount of life did not survive those changes (and much of those species that survived were able to do so because they could adapt and evolve to the slowly changing conditions). As I’ve pointed out before, the Earth will survive global warming just fine. It is human civilization or our species itself that is at risk.

# Growing Body Parts

There has been some exciting work regarding the growing or re-growing of human body parts.

Some animals have an incredible ability to regenerate missing body parts—a classic example being some species of starfish. However, for the most part, it is not possible to regrow complex organs. In humans, damaged tissue usually is replaced by “generic” scar tissue, if it all. There are several reasons why humans cannot regenerate most body parts. For one, once cells become specialized, they often lost the ability to divide. Another reason is that arms and hearts and so on develop according to a specific pattern during embryonic development in the womb; there is no “program” for starting with part of a fully-developed structure and regrowing the rest. And furthermore, there is some evidence that the ability to regenerate has been sacrificed to avoid cancer. Cancer is essentially uncontrolled cell growth; many checkpoints that help regulate this may also prevent stem cells from recreating damaged tissue. Presumably, this balance reflects an optimum balance for the survival of our ancestors.

But scientists are working to augment this ability. As New Scientist reports, researchers in Japan were able to grow tooth buds in the laboratory, then transplant them to the jaws of mice where they developed into normal teeth; they even developed a blood supply. Also reported in New Scientist is the efforts of American researchers to grow new ligaments in the laboratory. Ligament injuries are quite common, and they tend to heal quite poorly.

Finally, LiveScience discusses regrowth of human fingertips after accidents, and mentions a few notable cases.

# Retinal Implant Helps Restore Vision

The major components of the new prosthesis. The small wearable computer is not included. Credit: Mark Humayun/AAAS. Source: New Scientist.

An article by Gaia Vince in New Scientist reports on a retinal prosthesis designed to help restore vision to blind people. After a prototype was successfully used in six people, further trials are set to begin. While cochlear implants are used to give deaf people some ability to hear, there has been no comparable, practical system for those who cannot see.

The system has several components. The user wears a pair of glasses with a built-in camera. The information is then transmitted to a wireless computer around the size of a mobile telephone that the user must keep with him. This computer processes the data, then transmits it to a receiver implanted in the user’s head. This is connected to a chip on the user’s retina. This all occurs extremely quickly, as discrepancy between perceived movement and visual changes would cause nausea and dizziness.

The device is still preliminary; the resolution is quite limited, naturally. But it is interesting that the brains of the patients seem to adapt to the limited visual input, and their vision improved over time. The article notes one patient’s observation:

At the beginning, it was like seeing assembled dots — “now it’s much more than that,” says Terry Bryant, aged 58, who received the implant in 2002 after 13 years of blindness. “I can go into any room and see the light coming in through the window. When I am walking along the street I can avoid low hanging branches and I can cross a busy street.”

Similar to the cochlear implant, an intact nervous system is required. This prothesis links with the ganglion cells at the back of the eye and the signals travel over the optic nerve to the brain. Damage to any of these components—such as damage to the ganglion cells, injury to the optic nerve, or stroke—will result in blindness that this prosthesis cannot correct. For that, we’ll have to wait for new technology.

# Equations on WordPress

WordPress.com just added support for using inline $\textrm{\LaTeX{}}$ [Wikipedia], a freely available protocol for using typesetting and displaying mathematics and other technical information. It is powerful and not too difficult to learn the basics. Equations can now be placed within a paragraph, such as Einstein’s famous and world-changing $E=mc^2$. Of course, one could use regular HTML to display such an equation (E=mc2), but where $\textrm{\LaTeX{}}$ really shines is for more complex formulas. For instance, the volume of a sphere (using a cylindrical coordinate system) is $V=\int_0^{2\pi} \int_0^R \int_{-\sqrt{R^2-r^2}}^{\sqrt{R^2-r^2}} r \, dz \, dr \, d\theta = \frac{4}{3}\pi R^3$. This is a very useful feature and I’m quite impressed that WordPress.com has offered it.

Update: WordPress.com has been busy! $\textrm{\LaTeX{}}$ has now been enabled in comments as well. Furthermore, by using the\displaystyle command, one can have the equation display separately on its own line, instead of the vertically compact inline style used above. For instance, the volume equation I previously discussed would be displayed as follows:

$\displaystyle V=\int_0^{2\pi} \int_0^R \int_{-\sqrt{R^2-r^2}}^{\sqrt{R^2-r^2}} r \, dz \, dr \, d\theta = \frac{4}{3}\pi R^3$

For those unfamiliar with $\textrm{\LaTeX{}}$, it is really quite easy to learn. For reference, the code I have used here is as follows:

• $latex \textrm{\LaTeX{}}$
• $latex E=mc^2$
• $latex V=\int_0^{2\pi} \int_0^R \int_{-\sqrt{R^2-r^2}}^{\sqrt{R^2-r^2}} r \, dz \, dr \, d\theta = \frac{4}{3}\pi R^3$
• $latex \displaystyle V=\int_0^{2\pi} \int_0^R \int_{-\sqrt{R^2-r^2}}^{\sqrt{R^2-r^2}} r \, dz \, dr \, d\theta = \frac{4}{3}\pi R^3$

Finally, $\textrm{\LaTeX{}}$ is pronounced with a hard k sound at the end; it comes from the Greek letter Χ (chi). See Wikipedia for more information.

Any questions?

# DNA Animations

PZ Meyers posted a neat animation on his weblog “Pharyngula” the other day. The first part shows DNA coiling and packaging; the second part DNA replication.

They’re from a web site called DNA Interactive; you can see more excellent animations there.

I especially like these because they portray the complexity and beauty of these ubiquitous cellular processes, yet also exhibit their chemical, mechanical nature. We tend to personify biological phenomena (“the DNA unwinds, then adds complementary base pairs to each strand”); it’s easy to forget that these are essentially mechanical, step-by-step processes.

And yet they’re still beautiful.