Why do the trees change color in the fall?

It seems a fairly obvious question for this time of year. My daughter asked me this question last week, and I was embarrassed that I didn't know what to tell her.

According to News@nature.com, color change in leaves is not very well understood. The predominant theory is that leaves change their color in order to recycle the last bit of nutrients from their leaves before they are lost. Thus, trees grown in areas with less soil nutrients will produce more brilliant leaf colors.

As the weather turns colder, the trees switch to winter hibernation mode. The green chlorophyll in the leaves breaks down and disappears, revealing the yellow carotinoids that have been lurking among the chlorophyll all summer. The brilliant red color that people admire comes from a pigment called anthocyanin, which trees produce in autumn. Why trees expend their precious energy producing anthocyanin is still a matter of study and debate. It is believed that anthocyanin acts as a sunscreen, protecting leaves which are more vulnerable to sun damage after the chlorophyll is gone. The protected leaves can stay on the trees longer, allowing leaf nutrients to be absorbed into the other parts of the tree. link

Gravity victorious in rocket competition

NASA held their 2007 X Prize Cup rocket expo this past weekend near Alamogordo, New Mexico. The weekend's big event was the Northrop Grumman Lunar Lander Challenge, offering 1.35-million dollars in prize money to the company that can demonstrate a new space vehicle capable of landing humans on the moon.

Of the nine companies that registered for the event, only Armadillo Aerospace of Mesquite, Texas was ready to go on launch day. Armadillo is headed by John Carmack, the creator of the video game Doom. Their entry, Module 1, failed the test the first two times and exploded on the third. Interestingly, Armadillo was the only entry to show up for the 2006 competition, and its entry crashed that year, too.

Why is it that a team can't meet the challenge? It's not exactly rocket science. link

Some Neanderthals were redheads

The journal Science reports that at least 1 percent of Neanderthals were fair-skinned redheads. This adaption likely helped the Neanderthals of the high latitudes synthesize vitamin D with less sunlight.

Separate teams isolated a version of a gene called mc1r from the fossils of two different Neanderthals, one 43,000-year-old fossil from Spain, and another 50,000-year-old fossil from Italy. The Neanderthal version of the mc1r gene is similar to a gene found in humans that have fair skin and red hair.

The Neanderthal version of mc1r is not found in humans, which confirms that the gene samples were not mistakenly taken from a human. This also strengthens the currently-accepted theory that humans did not evolve from Neanderthals. link

Engineered virus shrinks tumors

Viruses have been known to shrink tumors. A reduction in tumor size can be observed after vaccinating a cancer patient, because vaccinating introduces a small amount of virus. The challenge has been to get enough virus cells to target the tumor without damaging healthy cells.

By genetically modifying the pox virus, David Kirn at Jennerex Biotherapeutics in San Francisco has engineered a special virus to seek and destroy tumors. Kirn's genetically-modified virus spreads more easily within tumors thanks to a tail composed of a protein called actin. Kirn has also modified the virus so that it is unable to produce an enzyme called thymidine kinase, without which the virus is unable to replicate and damage healthy tissue. Since cancerous cells contain an abundance of thymidine kinase, it is easy for the modified virus to multiply within tumors, and once the virus enters a cancer cell, it replicates itself until the cancer cell bursts. The third modification to the pox virus makes it produce a signalling molecule called cytokine, which attracts the body's immune cells towards tumors.

Clinical trials on the virus treatment was conducted with 13 patients with advanced liver cancer. The patients were so advanced that all previous therapies had failed, and they had a life expectancy of only three to four months. Beginning in July 2006, researchers started treating by administering the engineered virus directly into the participants' tumors every three weeks.

Seven of the participants survived for more than eight months, and three are still alive today, over 15 months later. The virus shrank the tumors of 10 of the 13 participants, including five whose tumors were reduced more than 50 percent. The only notable side effect experienced by the participants was temporary flu-like symptoms. link

Predicting global climate change: mission impossible

In the current issue of Science magazine, two University of Washington scientists suggest that we "call off the quest" for predicting global temperature changes, and that political decisions should not be made based on climate models.

For 20 years now, scientists have been working on predicting how much the average global temperature will increase when carbon dioxide levels reach double the pre-industrial levels. For all the effort, the predictions are not getting any more accurate -- current estimates range between 2.0 and 8.0 degrees C.

The article states that even the best computer models have too much uncertainty; this uncertainty comes from feedbacks in the system that change the way the system changes. For example, the sun is melting the polar ice caps. As they melt, they reflect less of the suns energy, changing the balance. These types of feedbacks cause uncertainty.

The article does not dispute that global temperatures will continue to rise; but nonetheless, the article will likely fuel the critics of the the climate change movement. link

Carbon dioxide emissions are still climbing

The greenhouse gas problem is nothing new, and you might think we've begun to at least slow our increasing carbon dioxide emissions. However, a paper published in the Proceedings of the National Academy of Sciences discloses more inconvenient truth.

In 2006, global carbon dioxide emissions resulted in a release of 9.9-billion tons of carbon into the atmosphere; 35-percent higher than the 1990 carbon emissions. In the atmosphere, carbon concentrations are now increasing at a rate of 1.93 parts per million (ppm) each year. This is the highest rate of increase since carbon monitoring activities began in 1959. The current rate of annual increase is considerably higher than the 1.58-ppm average for the 1980s and the 1.49 ppm for the 1990s.

Dr. Pep Canadell, the study's lead author and the Executive Director of the Global Carbon Project, explains that emission rates have likely risen as a result of the increase in global population and wealth. We have yet to find a way to increase increase global wealth without increasing carbon emissions rates. In addition, there has been a slowing of the effectiveness of global carbon-absorbing systems, such as rainforests and oceans. link

Flu spreads faster in cold weather

We can tell our grandmas they were right. New research from the Journal of the American Medical Association shows that the flu virus spreads easier in cold and dry weather. We used to explain that the increase in indoor activity in the colder months makes the flu season a cold-weather event. But, that's not the whole story.

The flu virus is exhaled from the body attached to aerosol water droplets. In as series of medical studies, the flu was spread through a population of guinea pigs. Since guinea pigs were in separate cages and do not sneeze or cough, the virus was spread only through breathing. Results showed that the flu spread much faster in colder air and in drier air.

When the air is dry, water aerosols and viruses move efficiently. But in damp air, the virus can't stay airborne; the aerosols containing the virus tend to combine with other water aersols and settle out of the air. Warm air can hold more moisture than cold air, so cold air tends to be drier and is better at spreading the flu.

After further study of the ginea pigs, researchers concluded that the spread of flu is also affected by the health of the mucus layers that line the nose and throat. In warm conditions, the mucus layer traps viruses and carries them from the body. Cold air damages the mucus layer, making the it more viscus and hindering the ability of the mucus to rid the infection.

So grandmas, bring on the chicken soup. link

A step closer Alzheimer's detection

More than 5-million North Americans are diagnosed with Alzheimer's decease, and a quarter of a million more are estimated to be living undiagnosed. Currently, doctors diagnose Alzheimer's by the patients' behavior and by eliminating other possible deceases. The only fool-proof way to diagnose the decease is after it's too late - through autopsy of the brain.

Researchers at the Stanford School of Medicine studied concentrations of communicode proteins the blood of living patients. The communicode is a set of 120 proteins that human cells use to communicate with each other. It is thought that the decease damages the communicode proteins in the brain and that these damaged proteins circulate throughout the bloodstream. Doctors diagnosed 20 patients with or without Alzheimer's. The blood test and the doctors' diagnoses agreed in 18 of 20 patients.

Unfortunately, even if diagnosed early, there is no current treatment for the decease. link

Mars orbiter snaps new high-resolution color images

Searching for the next Mars landing sights, the Mars Reconnaissance Orbiter captured 143 high-resolution color images of the planet's surface. The pictures are the first color images from the High Resolution Imaging Science Experiment (HiRISE) camera aboard the orbiter. The images are quite striking; they illustrate the unique geological history and chemical make-up of the planet's surface.

The next landing of a Mars rover will be in 2009. The unmanned rover, called the Mars Science Laboratory, will carry the next generation of instrumentation, searching for conditions that can or had once supported life on Mars.

Meanwhile, Opportunity and Spirit, the first two Mars Rovers, are still sending back data after more than three years of service. Not bad, considering the missions were expected to last three months. The aging rovers are beginning to fatigue due to the daily temperature swings of 200 degrees F. link

Memory shuts off just before sleep

What can we remember from surgery? What do we remember while dropping off - but not quite - asleep? Anesthesiology researchers say that we don't remember much.

Anesthetized patients were played a recording of words and sounds just before they went under. The patients brains were monitored through the whole process using functional magnetic resonance imaging. Although researchers observed brain activity in the part of the brain that recognizes language, the part of the brain that has to untangle language and meaning did not function well. After recovering, patients had difficulty identifying the last things they heard.

This finally proves what I've been telling you for 8 years about dozing off in class. link

Al Gore wins Nobel Peace Prize for work on climate change

Congratulations to Al Gore and the Intergovernmental Panel on Climate Change (IPCC) for claiming the Nobel Peace Prize. Gore has been a widely-visible spokesman for the climate change cause. The IPCC is a central repository for climate change research that collects and organizes the results of all climate change research, and then compiles plain-language summaries for the World's governments. Although the work of Gore and the IPCC is largely scientific, the work was viewed as an act of peace based on its intergovernmental nature. link

There are persuasive arguments to debunk Gore's film An Inconvenient Truth. The film may contain some partial and convenient facts (link), but the science of the matter is conclusive. The Earth is getting warmer and we are the cause. link

The appendix is good for something afterall

Back in my teaching days, I occasionally gave a lesson on useless body parts. The list would include discussions on the wisdom teeth, the sinuses, the coccyx, and male nipples. Students were surprised to learn that we still have muscles specifically for hanging from trees or walking on all fours, and that women have sperm ducts in their ovaries.

Until recently, the appendix was a regular on the useless list. This 4-inch-long sac at the juncture of the small and large intestines is known mostly for getting infected and bursting. Recently, researchers at the Duke University Medical Center have concluded that the appendix has a back-up role in the digestive process. The appendix stores a variety of good bacteria, the kind that healthy intestines use to break down nutrients. These bacteria can be deployed to repopulate the intestines after a catastrophic decease and diarrhea clears the contents of the intestines.

Now, what about those male nipples? link

Chilli powder: a cure for pain

The thing that makes the dentist's drill bearable is local anaesthetics. Local anaesthetics work rather haphazardly; they block not only pain channels but all the message channels in your nerve cells. The result is a loss of all sensation and temporary paralysis in the affected area; thus, the drooling.

But there are more serious problems with local anaesthetics. Take, for example, the epidural, a common childbirth procedure in which an anaesthetic is injected directly into the mother's spine. The process ameliorates the pain of childbirth, but leaves the mother's body unable to push out the baby.

It was reported in Nature that capsaicin, the active ingredient in chili peppers, has the ability to specifically activate pain channels in nerve cells and leave all other channels alone. When capsaicin is injected along with a local anaesthetic, pain channels can be targeted by the capsaicin and closed by the anaesthetic, allowing pain sensation to be blocked without loss of other sensations and without paralysis. Since the anaesthetic and capsaicin are already approved for the drug market, use of capsaicin in pain therapy is expected to be available soon. link

Sputnik turns 50

Fifty years ago today, the USSR successfully launched the first ever man-made Earth satellite. The orbiter was nothing more than a beachball-sized metal sphere that contained a radio and batteries to emit a beeping signal. The beeping little orbiter, named Sputnik, carried on for about two days before it faded into oblivion. Many Americans recall the eerie bleeping that was received by radio operators and replayed on radio and TV newscasts.

Those of us who were not around back then may be surprised to learn the emotional toll that Sputnik caused on most Americans. The Sputnik program was held completely secret to the public. It as only until after the launch that Americans (and even the Russian populace) heard the shocking news. In the height of the cold war, the thought that communist Russia had technologically surpassed the US was distasteful to most Americans, not to mention scary. If communists can put a radio beacon in orbit that can fly over America every 90 minutes, many Americans worried about what would come next - a spy satellite, or worse a warhead.

It was a real wake-up call to the US space program. President Kennedy announced the goal of landing on the moon within 3 years. The space race was on, thanks to that beachball in orbit. link

Radio burst puzzles astronomers

The Parkes radio telescope in Australia picked up a single, quick blast of radio waves that contained as much energy in its mere 5-millisecond duration as the sun puts out in a month. The signal was by far the strongest short signal radio astronomers have ever observed, and no previously-detected cosmic radio burst has the same set of frequency characteristics. After analysis, it was estimated that the radio burst came from 3-billion light-years away.

Astronomers know of only two possible sources of the burst: either the merger of two neutron stars or the final gasp of a dying black hole. Whatever the source, "it's bound to be exciting," says radio astronomer Lawrence Rudnick of the University of Minnesota, Minneapolis. The source is likely to "push us into exciting new realms of physics." Astronomers are searching archives for similar phenomena. Meanwhile, we'll stay tuned for more. link