Macchiarini described his latest progress and ideas for the future, including an ambitious plan to regenerate brain tissue, at the AAAS Annual Meeting. 

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Macchiarini described his latest progress and ideas for the future, including an ambitious plan to regenerate brain tissue, at the AAAS Annual Meeting. 

When an organ fails, transplanting a new one is often the only solution, but there is a grievous shortage of donor organs available. The risk that the patient’s immune system will reject the new organ is very serious too, and many transplant recipients face a lifetime of immune-suppressing drugs.

Paolo Macchiarini speaking at the AAAS Annual Meeting. Credit: AAAS Staff.

The emerging field of regenerative medicine aims to find ways around these problems. Typically, several components are used together, according to Macchiarini. These include tissue engineering, which can involve stripping a donated organ of its cells, leaving just connective tissue behind, or constructing an artificial matrix from synthetic materials. This scaffold is then seeded with a patient’s own stem cells, which can develop into more specific cell types. Such cells might also be injected directly into the body, without the scaffold, an approach known as cell therapy. Drugs that promote tissue growth also help the new material settle in and heal damaged sites.

For more complex organs such as the heart, lung or liver, repairing just the damaged spots with cell therapy is more realistic than growing and transplanting a full-fledged organ, Macchiarini said.

Researchers using this approach generally grow certain types of stem cells in culture before transplanting them. “But we could do this differently,” Macchiarini said, and inject the cells locally so they would differentiate on-site and stimulate some of the body’s own healing processes.

Macchiarini and his colleagues used this strategy on a patient whose larynx had lost its blood supply. The operation saved the larynx so it didn’t have to be removed. 

Two patients with acute lung failure also received stem cell-based therapy and showed improvement. Although both patients died due to multi-organ failure, the results have indicated that stem cell therapy can be a promising method for restoring function in some damaged organs.

It might even be possible to regenerate functioning brain tissue, according to Macchiarini. “You might think I’m crazy,” he said. “Well, I probably am, but I think of the soldiers that are shot in the world, the car accidents.” 

He is currently working on removing the living cells from a rat brain and adding a gel-like matrix of nanofibers seeded with proteins that protect neurons and attract stem cells. His hope, which has been supported by experiments in mice and rats, is that this gel could be administered to the site of a brain injury to salvage the damaged tissue. 

Macchiarini is also continuing his work with trachea transplants, developing a trachea completely from scratch instead of starting with a donated one. This approach would allow him to build a structure that would fit in a young child, for example, and that would be less likely to degrade over time.

He plans to transplant such a trachea in a 2-year-old girl in March. The girl was born without a trachea and has lived her entire life in intensive care, where she breathes through a tube placed in the esophagus and connected directly to the lungs. This will be the first time the procedure is conducted on a small child and on an individual without any trachea at all.

Did this rap win the "America's Scientist Idol" competition at the AAAS Annual Meeting? Scientists had three minutes to hook a panel of judges and a packed audience on their research and why it matters. In a Science podcast, Kerry Klein talks to the host and the crowned champion.  

"What it did with this long neck I can only speculate," said Olivier Rieppel, Curator of Evolutionary Biology at the Field Museum in Chicago, who led the team that identified the Dinocephalosaurus skeleton. This 5-meter-long creature might have splayed out the ribs in its neck to create suction for drawing prey into its mouth, Rieppel proposed at the AAAS Annual Meeting. 

Illustration of Dinocephalosaurus Orientalis showing the body proportions, including its long neck. Credit: Courtesy of The Field Museum/artist Marlene Donnelly

But then Kenyon’s lab uncovered a single gene mutation in roundworms that doubled their lifespan, and aging became one of the hottest topics in biology. As she told her audience at the AAAS Annual Meeting, scientists began to see the process of getting older as a newly dynamic force. Now, she and others are searching for ways to manipulate the process to allow humans to live healthier and longer lives.

Read the full story from Becky Ham »

But then Kenyon’s lab uncovered a single gene mutation in roundworms that doubled their lifespan, and aging became one of the hottest topics in biology. As she told her audience at the AAAS Annual Meeting, scientists began to see the process of getting older as a newly dynamic force. Now, she and others are searching for ways to manipulate the process to allow humans to live healthier and longer lives.

“It wasn’t so long ago that aging was something that just happened,” like a car slowly breaking down, said Kenyon, who serves as director of the Hillblom Center for the Biology of Aging at the University of California, San Francisco.

Cynthia Kenyon speaking at the AAAS Annual Meeting on aging and biology. Credit: Atlantic Photography Boston

But, most major biological events do not just unfold on their own. Instead, she noted in her Plenary Lecture, they are subject to an “incredibly complex system of regulation by genes and proteins.” It seemed to Kenyon that aging might have its own complicated backstory.

That story sprang to life with the 1993 discovery of the roundworm daf-2 gene in her laboratory. Worms with a mutation in the gene lived twice as long as their peers, Kenyon said, and were much more spry than those companions in the worm “nursing home.”

The daf-2 gene extends lifespan through a molecular pathway leading to another key gene called daf-16; daf-2 sends signals to daf-16, prodding it to begin switching a variety of other genes on and off. Over the years, Kenyon’s lab and others have explored the details of this key relationship, discovering that mutations in these genes affect a number of important jobs in the cell, including protection against stress, protein folding, metabolism and immune response.

At the same time, laboratories around the world have uncovered equivalent genes in mice, fruit flies and humans, including a human counterpart of daf-16, called FOXO3A, that has been associated with exceptional longevity in populations around the world, Kenyon said.

Under normal conditions, the daf genes—and their counterparts in humans—help cells grow and thrive. When daf-2 is mutated, however, the cells read this as a danger signal and mount an impressive protective response. The worms become “resistant to just about anything you can do to them,” Kenyon said, including staving off the effects of heat, cold, drying and toxins.

It’s this response that slows the rate of aging and leads to longer lifespan, Kenyon noted. She compared it to a proactive building maintenance supervisor who wisely watches the weather report and boards up the windows in advance of a storm.

Kenyon’s lab and others are searching for ways to bring on these storms, albeit in a controlled way, to trigger the protective response. Restricting calories, lowering rates of respiration and removing the cells that give rise to eggs and sperm are a few of the methods that researchers have used to extend animal lifespan in the lab.

The search is now on to find small molecules that could be used to manipulate aging’s molecular pathways. “These pathways that slow aging also have the wonderful property of counteracting age-related disease,” Kenyon said. 

Researchers have documented lower rates of cancer, cardiovascular diseases and Alzheimer’s-like disorders in mice with these aging mutations, she said. 

The story of these discoveries, Robert Kirshner said at the AAAS Annual Meeting, includes luminaries both human and cosmic. Supernovae, the massive and bright star explosions that he studies, were crucial to piecing together this new understanding. But, Kirshner also talked about the people, including two of his graduate students who won the Nobel Prize, whose work gradually revealed an accelerated universe.

Read the full story from Becky Ham »

The story of these discoveries, Robert Kirshner said at the AAAS Annual Meeting, includes luminaries both human and cosmic. Supernovae, the massive and bright star explosions that he studies, were crucial to piecing together this new understanding. But, Kirshner also talked about the people, including two of his graduate students who won the Nobel Prize, whose work gradually revealed an accelerated universe.

In his Plenary Lecture, the Harvard University astrophysicist led listeners through 13.7 billion years of cosmic evolution, and 100 years of research—and even managed to eat a modest slice of pumpkin pie along the way. 

Robert Kirshner speaking about The Accelerating Universe at the AAAS Annual Meeting. Credit: Atlantic Photography Boston

More about that pie in a moment, but the scientific story starts in 1917, when “Albert Einstein thought the Milky Way was more or less equal to the universe,” Kirshner said. Einstein also thought the universe was unchanging, and his equations describing it included a repulsive force that he called the cosmological constant. The cosmological constant was Einstein’s way of explaining why the stilled universe did not collapse in on itself from the gravitational pull of all the stars and other matter it contained.

Around the same time, Harvard College Observatory astronomer Henrietta Swan Leavitt showed that the luminosity of certain “variable stars” was related to fluctuations in their brightness. The longer the period between fluctuations, the more luminous the star was. These variable stars became the first “standard candles” to light the way in exploring the size and dynamics of the universe, Kirshner noted. 

Researchers already knew that stars should become increasingly dim the farther they were away from Earth. With variable stars now offering a standard measurement of brightness, astronomers could calculate exactly how far these stars might be, depending on how dim they were. 

The discovery confirmed that the universe was bigger than the Milky Way, but it also revealed another surprising fact to astronomer Edwin Hubble in 1929. When he and others closely examined the wavelengths of light coming from these stars, they were able to see shifts in the wavelengths that correspond to direction and speed. The stars, Hubble concluded, were moving away from each other and the universe was expanding.  

Leavitt’s variable stars are too dim to be seen at the far edges of this expanded universe, and now Type 1a supernovae, among the brightest objects in the sky, are the new standard candles. They burn “four billion times as bright as the Sun for about a month,” Kirshner said. But “they are really, really rare. There’s only about one per century in a galaxy.”

Kirshner and his graduate students Brian Schmidt and Adam Riess would have to use computers and increasingly better cameras to scour thousands of galaxies for the supernovae, but their efforts paid off. In 1998, they reported that the expansion of the universe is accelerating. Schmidt and Riess, along with Saul Perlmutter, won the 2011 Nobel Prize in Physics for the discovery.

The cosmological constant, which Einstein had disavowed when Hubble discovered that the universe was expanding, has new relevance in modern cosmology. Something has to be giving the universe its “springy quality,” Kirshner said, and it might just be Einstein’s repulsive force.

The cosmological constant could represent what astrophysicists call “dark energy.” Dark energy may make up as much as 73% of the total universe, with unseen cold dark matter making up an additional 23%. Only 4% of the universe is made up of visible matter, a fact that Kirshner illustrated by slicing and eating a sliver of pie on the AAAS stage. It may not look like much, he joked, “but it’s the tastiest component of the universe.”

What does the future of an accelerated universe hold? In four billion years, the Milky Way Galaxy is expected to collide with the neighboring Andromeda Galaxy. After that, Kirshner said, the distances between the Milky Way and all other galaxies could be so great that the Milky Way will appear as Einstein first considered it: a universe unto itself.

Aquaculture—an industry that has experienced dynamic growth—could make a major contribution to the world’s protein needs, researchers said at the AAAS Annual Meeting. They were also candid about challenges ahead; namely, ensuring that fish-farming is sustainable as it is scaled up.

Read the full story from Meagan Phelan »

Aquaculture—an industry that has experienced dynamic growth—could make a major contribution to the world’s protein needs, researchers said at the AAAS Annual Meeting. They were also candid about challenges ahead; namely, ensuring that fish-farming is sustainable as it is scaled up.

This means ensuring that aquaculture facilities don’t degrade the environment and that fish feed is high-quality and not in competition with human food sources. “This is particularly critical in light of issues around global food security,” said Jeff Silverstein, National Program Leader in Aquaculture at the USDA Agricultural Research Service.  

Photo of several production systems at Bell Aquaculture. Courtesy of Bell Aquaculture.

Fish production is “by far the most efficient source of animal protein production today,” Silverstein said. Fin fish and shrimp, for example, require about one pound of feed to produce one pound of meat, compared to poultry, which requires two pounds, and pigs, which require three, according to Silverstein. 

To meet the global seafood appetite, aquaculture will need to “integrate the many improvements being developed in separate sectors, like nutrition and fish-production systems,” Silverstein said.

One such improvement is the development of feed that is high quality, meeting all the nutritional needs of fish but excluding ingredients consumed by humans. 

“In a world with an ever-growing population, how sustainable is it to continue feeding fish ingredients that humans need?” asked Margareth Overland, professor at the Norwegian University of Life Sciences. These ingredients include things like fish oil and plant-based products. “Fish feed of the future needs to be based primarily on non-food raw materials,” she said, “and I am studying some promising products.”

These include microbial organisms like yeast, which have the ability to convert low-value biomass (such as wood) into high-quality feed ingredients. 

“What’s exciting here from a sustainability viewpoint,” said Overland “is that microbial ingredients not only can be produced from non-food raw materials, they also use very little water. From the production standpoint, they provide high-quality protein and other components that have health benefits.” Research shows that feed made from microbial ingredients supports fish growth and prevents intestinal inflammation, according to Overland.  

“The conversion of non-food materials into high-quality feed resources could truly help make aquaculture sustainable,” she concluded.

Another important consideration is fish-farm expansion, which has been constrained in the past by limited water resources, site access and regulatory limitations. 

At the Conservation Fund Freshwater Institute Shepherdstown, West Virginia, Steven Summerfelt and colleagues focus on increasing farmed fish production in systems that minimize water use. They have developed land-based, closed-containment systems that use water recirculation technologies. “This allows us to produce fish using a fraction of the water typically required on industrial fish farms,” he said. 

But that’s not the only benefit. “Our systems also allow us to capture the nutrients in the waste of the fish, for re-use, and they serve as effective barriers for fish pathogens.” The absence of pathogens eliminates the need for vaccination and improves fish welfare, Summerfelt said.

What’s more, these systems are scalable. They can be located just about anywhere, reducing the need to ship and refrigerate the fish. Proving the viability of these systems, a trial of Atlantic salmon raised in West Virginia showed a survival rate of 97%. 

“Right now, there are five land-based, closed-containment systems around the world, all showing good results,” said Summerfelt. “Twelve more are in the planning and construction stages. Their use could greatly expand domestic and global fish farming with minimal environmental degradation.”

Together, the solutions offered by these and other researchers show promise for sustainably increasing global fish production. “Integration of all these advances—that is what will be key,” Silverstein said. 

The technology of teaching hasn’t changed since the 14^th century, according to Norvig, who is the director of Research Google, Inc. But, that is about to change, with the growing popularity of Massive Online Open Classes, or “MOOCs.”

Read the full story from Jennifer Santisi »

The technology of teaching hasn’t changed since the 14^th century, according to Norvig, who is the director of Research Google, Inc. But, that is about to change, with the growing popularity of Massive Online Open Classes, or “MOOCs.” 

A number of online lecture platforms have emerged recently, such as Coursera, Khan Academy and Google Online Courses. Most of these programs provide a video lecture, and at the end students are prompted to interact in some way, achieving a feeling of community. Much of the buzz about MOOCs arose after Norvig and Google colleague Sebastian Thrun taught an online course on artificial intelligence through Stanford University, attracting over 100,000 registrants.

Peter Norvig. Courtesy of Peter Norvig.

The personal aspect of one-on-one tutoring enhances the way a student learns, said Norvig who himself was motivated to learn by his mother sitting with him as a child. MOOCs strive to bring the one-on-one learning experience to students via a computer. 

Currently, there is around a 10% completion rate for online courses, according to Norvig. Although that percentage may sound low, he compared it to Stanford, which rejects 90% of the students that apply. That leaves 10% that are completing the courses. MOOCs allow students to decide for themselves if they want to take a course, and students typically sign up for many classes and shop around for the one they will complete. 

About one third of online students are from North America, one third are from Europe and the rest are from other parts of the world, according to Norvig. Connectivity issues are still a challenge in the developing world, and some countries, like China, block certain video platforms such as YouTube. 

Access isn’t the biggest hurdle, however. “Information is not the problem, motivation is really the problem. The hard part is to get the student motivated,” Norvig said. 

Eighty percent of the online students already have college degrees. The majority of people taking the online courses are probably coming back to further their careers or looking to try something new. 

In an effort to discover what it means to learn, Norvig ended up reversing everything he knew about the role of the teacher. “It’s the students’ job to learn, and the teacher is there to facilitate that,” he said. “It’s important for students to make predictions. If they have the wrong answer somewhere in their head, the right answer won’t sink in.” 

Principles of software engineering lend themselves to this type of learning process, via MOOCs, according to Norvig. The idea of “Test-Driven Development,” for example, is that programmers initially write the tests a program has to pass, and then write the software so that the program can pass all the tests. This approach can also apply to human learning, he said.

There are other advantages to online courses, Norvig explained. Students can replay the videos, unlike in-person lectures, and they don’t have to feel embarrassed about asking a professor or a tutor to repeat information. Online courses also promote discussions and feedback from peers, he said. 

Online courses should be designed according to four main tenets, Norvig concluded. They should mimic one-on-one tutoring; have a sense of community; be a high-quality resource for education; and use machine learning classification techniques to gather data and make improvements. Applying these ideas, he said, helps motivate people to learn.

The plummeting costs and wider accessibility of DNA sequencing technology are ushering in new prospects for personalized genetic medicine. They are also prompting serious discussions around the profound societal implications of using patients’ genomic data in medical care.

Read the full story from Meagan Phelan »

The plummeting costs and wider accessibility of DNA sequencing technology are ushering in new prospects for personalized genetic medicine. They are also prompting serious discussions around the profound societal implications of using patients’ genomic data in medical care.

Experts gathered in Boston to examine these issues at the AAAS Annual Meeting. They also discussed engaging with the public to improve understanding of DNA sequencing technologies, a particularly critical strategy as these technologies become more widely available. 

The sequencing work done by 23andMe and research institutions the world over has moved the field of genomics to an exciting moment, when researchers—equipped with a critical mass of genetic data—can finally focus on deciphering what this data means and how it might influence risk for certain diseases.  

Expert panel. Credit: AAAS Staff.

This work is pivotal considering much of the genome remains a mystery. “Almost everything in the human genome is a variant of unknown significance,” said 23andMe founder Brian Naughton. 

Determining which gene variants are clinically significant is no simple task. Labs pursue this process very conservatively. For example, even if a lab discovers a mutation, that mutation must meet certain criteria—including having been found in other patients with a disease and being known to impact protein production—to be deemed clinically significant. According to Mira Irons of Boston Children’s Hospital, “Since we are seeing so much more data now, we will inevitably see things we’ve never seen before, and that will make determining clinical significance even harder.”  

Ensuring that genomic information is useful to physicians and patients presents yet another challenge. Doctors must be able to interpret genomic datasets in a way that is meaningful for their patients. 

“We are finally at the point where genetics and genomics will impact medical care,” explained Irons, “but we haven’t given healthcare providers the information they need to use results effectively.” She has facilitated this process at Boston Children’s Hospital by bringing trained geneticists to work alongside healthcare providers to help them understand sequencing results. 

The panelists also touched on strategies for sharing the results of genome sequencing with people who have little background to understand them. The fact that genetic influences are not deterministic is important to get across, for example. “We also need to convey the difference between uncertainty and risk,” said Ting Wu, a professor in Harvard Medical School’s Department of Genetics. “Knowledge of risk gives the option for action.” 

In addition to explaining information accurately, doctors will need to answer some thorny questions as they care for their patients, such as how much information to give these individuals about their genomic sequencing results, said Jonathan Gitlin, Science Policy Analyst at the National Institutes of Health. 

Permission from patients is another issue. “Acquiring informed consent from a patient being tested for a single mutation is relatively straightforward, but if you are going to sequence that person’s entire genome, how do you get accurate informed consent to account for the ample findings that could result?” Gitlin added.

Sheila Jansanoff, Professor of Science and Technology Studies at the Harvard Kennedy School, discussed even broader implications of next-generation sequencing technology. For example, because people are able to order genetic testing results directly, they can be more active in understanding their own healthcare and less dependent on physicians. 

Despite the complexity that remains to be addressed, what is before us is not a DNA dilemma, but an opportunity, according to Wu. “Among my colleagues is an understanding that we have an obligation to make sure we share what we learn,” she said. “Furthermore, science writers are getting it right, explaining genetics in words anyone can understand—and the public wants it; they are very vocal. Overall, we’re doing a better job conveying information than we have in past. I am optimistic.”

Schellenberg, a University of Toronto psychologist, said his studies showed instead that children who take music lessons tend to be more conscientious and open to new experiences than their peers. These are the same sorts of personality traits, he said, that also are associated with high IQ and doing well in school.

Read the full story from Becky Ham »

Schellenberg, a University of Toronto psychologist, said his studies showed instead that children who take music lessons tend to be more conscientious and open to new experiences than their peers. These are the same sorts of personality traits, he said, that also are associated with high IQ and doing well in school.

Daniel Levitin, Glenn Schellenberg, and moderator Earl Lane. Credit: AAAS staff.

When researchers account for these personality traits, the link between cognition and music training suggested by some previous studies disappears, he said.

These findings don’t mean that children should stop taking lessons or enjoying music, Schellenberg said. “To justify music in terms of its spillover effects into nonmusical domains is a complete waste of time, and it’s like saying that music would be irrelevant or useless without those nonmusical benefits.”

Extra piano practice may not translate into extra intellect, but is there a way to determine which people have a special talent for music and might benefit from lessons? Neuroscientist Daniel Levitin said there aren’t many good tests for this kind of aptitude.

“We don’t have tests that predict from a young age who is going to excel at music,” he admitted, “and we don’t have tests that we can give to adults to correlate well with achievement.”

Levitin spoke about a colleague who gave one of the more popular musical aptitude tests to members of the Los Angeles Philharmonic, and “half of them scored in the lower half of the test,” he said.

He thinks that researchers “would benefit from a broader definition of musicality,” which would include not just people who can read music and play virtuoso cello, but also people like DJs with a knack for putting together a playlist and those who are profoundly moved by music.

Levitin’s work is informed by his own broad musical roots; he produced records for Santana and Blue Oyster Cult and performed with Sting and Roasanne Cash before becoming a scientist. 

“I think there are benefits to society to having more people engaged in the arts,” he said. Even if music instruction doesn’t make you a better mathematician or a better athlete, even if it only gives you the enjoyment of music, that’s a good end in and of itself.”

While efforts to reduce the blood lead levels in children the United States have been largely successful with the elimination of leaded gasoline and restrictions on lead paint, lead pollution internationally remains a pressing issue.

Read the full story from Meagan Phelan »

While efforts to reduce the blood lead levels in children the United States have been largely successful with the elimination of leaded gasoline and restrictions on lead paint, lead pollution internationally remains a pressing issue.

Recycling of lead acid batteries, for example, is a major source of lead in developing countries.

“There are neighborhoods outside Jakarta, Indonesia, where 300,000 tons of lead acid batteries are recycled each year in informal factories,” said Mary Jean Brown, Chief of the Centers for Disease Control and Prevention’s Healthy Homes/Lead Poisoning Prevention Branch. “There are no barriers between the people in those villages and the lead toxins the recycling process creates.” 

Consumer products made with recycled lead find their way from developing nations into international markets, including the United States. In 2012, for example, U.S. customs officials seized 1,400 Halloween costumes imported from China that contained 11 times the permissible lead level. 

Dr. Brown said that the knowledge and skills required to address the international lead issue currently exist. “Now we must develop the leadership in developing countries to disseminate information about lead safety concerns.”

Exacerbating the problem, lead is spread through the atmosphere; so, while lead pollution has gone down in some parts of the world, industrial activities elsewhere mean lead released into the environment in one country could easily spread somewhere else.

Members of Dr. Howard Mielke's research team improve the soil environment at a New Orleans daycare center by spreading clean soil (less than 5 ppm lead) over a geotextile layer. Credit: Howard Mielke

In the United States, one researcher is focusing on lead that has settled to the ground under our feet. Howard Mielke, professor of pharmacology at Tulane University School of Medicine, has studied the association between lead in the soil and lead in the blood of children. More specifically, he has investigated how high levels of lead in urban soils affect human welfare. Lead poisoning permanently affects the brain’s prefrontal cortex, where vital cognitive functions take place. 

“Children who grow up in areas with high soil lead are both less successful in school and more aggressive later in life,” Mielke explained. 

His work could shed light on changes in rates of violent crimes nationwide; in 2010, for example, researchers observed that cases of violent crime by young males in the United States had decreased sharply since the 1990s. Mielke’s work shows that the declines in aggressive behavior by 1990 more or less parallel the efforts begun in the early 1970s to reduce atmospheric lead from automobile exhaust, and in turn, in the blood lead levels of children born at that time.

Mielke and his team have found high levels of soil lead (500-1000 parts per million) in neighborhoods of New Orleans. To advance lead poisoning prevention in the most at-risk locations, Mielke has developed methods for reducing lead in the topmost layers soil.  One method involves placing a geotextile layer over the contaminated soil and then bringing in new, clean soil to lay over it.

The X-ray of a common loon killed by lead poisoning. The small bulb in the loon's stomach is a lead fishing angler. Credit: Mark Pokras

The persistence of lead poisoning in the United States is underscored by results in animals. “I see five to eight cases of lead poisoning in my clinic per week,” said Dr. Mark Pokras, a veterinarian at Tufts Cummings School of Veterinary Medicine. “This is something that should be totally preventable.” 

The lead Pokras finds in the animals he treats often comes from unexpected sources, like fishing tackle or bullets. Legislation to reduce the lead in hunting equipment is still being pursued.

“Given what we are learning about the many toxic effects of lead, there is every reason to develop and adopt non-toxic alternatives for fishing and hunting equipment,” Pokras said. 

To accomplish this, he said, all interest groups must work together to find safe alternatives and to develop new educational and policy initiatives.

Pokras and other experts also discussed the impact of lead and other contaminants on our health in a Google+ Hangout, hosted by ScienceLive at 3:00 pm on Sunday afternoon.

But the Penn State geologist said governments should be worrying about the worst-case scenario—a rapid disintegration of major ice shelves in places like western Antarctica—because researchers can’t rule out that possibility and the impact would be devastating.

Read the full story from Becky Ham »

But the Penn State geologist said governments should be worrying about the worst-case scenario—a rapid disintegration of major ice shelves in places like western Antarctica—because researchers can’t rule out that possibility and the impact would be devastating.

Policy-makers should take precautions akin to those in place for the morning commute, Alley said, where the most likely scenario is just slight traffic snarls and bad radio songs like “Muskrat Love.” “What we expect as commuters is a world that is almost as good as it can be,” he said. “But the most likely, the most expected, is way out on the good end of outcomes.” 

Because we know this, cars are equipped with seat belts, children’s car seats and airbags as precautions against the worst commuting scenario of being killed by a drunk driver.

“We put a lot of our travel budget into some things that we do not expect to happen, because it’s such a big deal, and we can’t really predict it,” Alley said, suggesting that a similar logic should apply to the possibility of a major ice sheet collapse.

Alley participated in the Intergovernmental Panel on Climate Change (IPCC), a co-recipient of the 2007 Nobel Peace Prize. As he has talked with policymakers and economists about the IPCC’s findings, he has found that many of them think sea-level rise will be “slow, small and expected” and not overly disruptive to the economy and society.

An iceberg in or just outside the Ilulissat fjord that likely calved from Jakobshavn Isbrae, the fastest flowing glacier in west Greenland. Courtesy of Ian Joughin

There is some scientific evidence to support this view, Alley said. Estimates of major ice-sheet melt come out to 0.6 millimeters per year, contributing about 20% to observed sea-level rise. At this rate, it might take more than 100,000 years for the ice sheets to disappear. 

Alley compared this decrease to going on a diet but only omitting the calories from one-third of potato chip in a year. “The worry is about what if the ice sheets get serious about dieting?” he said.

As might be expected from the 2012 winner of the AAAS Public Engagement with Science Award, Alley outlined this danger with a few instantly grasped analogies.

Ice sheets are big piles, he explained, which spread underneath their own considerable weight, slide into the sea, melt and contribute to sea level rise.

Much attention has been paid attention to how melting may lubricate the bases of ice sheets and speed up this slide. But, the bottom of the Greenland ice sheet, at least, is more like a greased waffle iron than a greased pancake griddle, Alley said. The meltwater does contribute to some sliding, but the rough, corrugated ground under the ice sheet grips the ice tighter than a flat surface might. 

It’s the ice shelves at the edges of these ice sheets, which act like the supportive flying buttresses in a Gothic cathedral, that are Alley’s greater concern. These shelves butt up against adjoining land, creating friction and holding the ice pile in place. When these shelves collapse—in some cases disintegrating within a few months—ice sheets become much more vulnerable to rapid melting.

Researchers are particularly concerned about this possibility occurring in western Antarctica, where the collapse of ice shelves could unleash ice flow that that has been building up for thousands of years behind “bumps” in the land.

Even if the “drunk driver” of ice-sheet collapse doesn’t arrive, Alley said economists should be wary of predictions that people will respond to sea level rise in a highly efficient manner.

He pointed out that government researchers had known about sea level rise, erosion in the Mississippi River delta and stronger Atlantic Ocean storms for 20 years before Hurricane Katrina drowned New Orleans in 2005.

Even under the best-case scenario, Alley said, “we are better off if we respond to climate change. Ignoring it is costly compared to dealing with it.”

Place frozen peas in a laboratory-grade centrifuge. Spin them so fast that they experience about 40,000 times the force of normal gravity for one hour.

And the serving suggestions? The final concoction consists of three layers: a clear and fresh pea bouillon, a thick layer of starch that can be used in pasta, and a rich substance that Myhrvold enthusiastically calls “pea butter.”

At the AAAS Annual Meeting, Myhrvold explained how science applies to the mysteries of meat and wine, illustrating his lively talk with descriptions of french fries crisped in an ultrasonic bath and describing the culinary pleasures of freezing olive oil with liquid nitrogen and smashing it into glassy shards. 

Read the full story from Becky Ham »

Place frozen peas in a laboratory-grade centrifuge. Spin them so fast that they experience about 40,000 times the force of normal gravity for one hour.

And the serving suggestions? The final concoction consists of three layers: a clear and fresh pea bouillon, a thick layer of starch that can be used in pasta, and a rich substance that Myhrvold enthusiastically calls “pea butter.”

Most everyday cooks won’t employ a centrifuge in their kitchens, Myhrvold admits, so he has developed a more user-friendly home edition of Modernist Cuisine, his six-volume manifesto on the science of cooking. But science has always been in the kitchen, he said. “Science is how the world works. It’s ignorance of science that I’m trying to remove from the kitchen.”

At the AAAS Annual Meeting, Myhrvold explained how science applies to the mysteries of meat and wine, illustrating his lively talk with descriptions of french fries crisped in an ultrasonic bath and describing the culinary pleasures of freezing olive oil with liquid nitrogen and smashing it into glassy shards. 

Nathan Myhrvold lecturing about the science of cooking. Credit: Atlantic Photography Boston

Myhrvold told the story of how he, the first chief technology officer of Microsoft Corporation and a theoretical physicist and applied mathematician, came to be freeze-drying basil in the laboratory. Today he serves as founder and chief executive officer of Intellectual Ventures, but Myhrvold began his second career as a chef at an early age: “When I was nine years old, I told my mom I was going to cook Thanksgiving dinner and chased her out of the kitchen.” 

Like scientists, chefs over the years from Auguste Escoffier, to Julia Child, to Spain’s molecular gastronomist Ferran Adrià have “developed empirical rules” along with their recipes. But, as chefs look for innovative ways to make a meal, Myhrvold said, they are less attracted to recreating dishes from a formula and more interested in learning why and how cooking works, as the basis for improvisation.

That’s where physics comes in, and Modernist Cuisine is “the only cookbook to contain partial differential equations,” he joked. 

Nathan Myhrvold’s Recipe for the Perfect Medium-Rare Steak

Choose a well-marbled cut of meat. Apply Fourier’s heat equation.

Fourier’s heat equation describes heat distribution in a region over time, and it explains why a hot pan may not be the best way to get a medium-rare steak to the plate. If the temperature difference between the hot pan and the interior of the steak is too great, Myhrvold said, a chef could end up with 30% of the steak well done before its interior reaches the perfect temperature. Fourier’s equation suggests that cooking at lower heat will bring the entire cut to medium rare at the same time, albeit at a slower rate.

And the physics of crispy french fries? They can get their crunch from cavitation in an ultrasound bath, where thousands of tiny popping bubbles scour the potatoes and increase their surface area for frying. The reason toast burns so easily? It’s all about albedo, Myrhvold said. Because toasting makes the bread darker, it decreases the slice’s surface reflectiveness. The bread’s ability to soak up heat thus increases exponentially. That’s why two minutes in the toaster is just right and two and a half minutes leads to a charred mess.

Mayonnaise and cream, two emulsions made from the suspension of droplets of fat in a second liquid, are opaque and white for the same reason that clouds are white: bending of light by the large suspended droplets, Myhrvold noted. Stripped of its fat globules, skim milk can be blue like the sky. In both cases, the colors are due to Rayleigh scattering, in which particles smaller than light’s wavelength cause the light to diffuse.

Nathan Myhrvold’s Recipe for Decanting Wine

Uncork wine, pour in blender. Blend to a froth. Serve.

Myhrvold said scientists are still not sure why decanting wine—pouring it into a wider vessel to increase the surface area of the wine—changes its flavor. It could be that decanting causes more oxygen to mix with the wine, or allows it to release dissolved gases like sulfur dioxide or other volatile chemicals. But the mystique surrounding wine, he suggested, makes it a perfect target for scientific exploration.

Blending can improve the flavor of young red wines and it’s faster than traditional decanting. But the real reason to do it, Myhrvold suggested, is to shock your dinner guests.

“It’s food!” he exclaimed. “Why is it OK for daiquiris, and not Bordeaux?”

While Pyenson described whales of the past, Megan McKenna, currently a bio-acoustic biologist with the National Park Service in Fort Collins, Colorado, spoke about present-day issues affecting whale populations. Working with the Scripps Institution of Oceanography, McKenna has measured ocean noise levels to study how chronic and acute ocean noise impacts whale communication. She discussed her work with Schaffer in a AAAS podcast.

Watch the video from Carla Schaffer »

[Video] Nicholas D. Pyenson of the Smithsonian National Museum of Natural History

Nicholas D. Pyenson, curator of fossil marine mammals at the Smithsonian National Museum of Natural History, brought marine mammals' terrestrial ancestors to life during the symposium "Evolution of Giants: The Great Whales" at the 2013 AAAS Annual Meeting in Boston. 

Recently Pyenson's work has taken him to excavation sites in the Cerro Ballena in Chile. 

"This is a 3D facsimile, a replica, of a snapshot in time of doing research," Pyenson said in an interview with AAAS' Carla Schaffer, holding the replica in one hand. "This actual specimen was part of a whole quarry of whale fossils and other marine mammal fossils that were discovered along the Pan American highway in 2010 by a road construction company." 

While Pyenson described whales of the past, Megan McKenna, currently a bio-acoustic biologist with the National Park Service in Fort Collins, Colorado, spoke about present-day issues affecting whale populations. Working with the Scripps Institution of Oceanography, McKenna has measured ocean noise levels to study how chronic and acute ocean noise impacts whale communication. 

[Audio] Megan McKenna discusses ocean noise and its effect on whales.