NSF SUPPORTS DIVERSITY WITH ASTRONOMY PROGRAM

FROM:  NATIONAL SCIENCE FOUNDATION 

Making stars

Astronomy program provides tools, support to enhance diversity

October 7, 2014

Like so many other children, Fabienne Bastien did not like to go to sleep at bedtime.

She recalls her mother lying alongside her, telling her to look out her window into the night sky because her guardian angel was there. And as she searched for this elusive guardian angel, what she found instead was the moon and stars, among other astronomical delights.

Despite Washington, D.C., metro-area light pollution that can restrict one's view of the cosmos, Bastien pinpoints that moment as the one when she got hooked on astronomy, knowing it held her future, if not an actual guardian angel.

Many astronomers and astrophysicists speak of that same source of inspiration. But, while our solar system's immensity and beauty have an almost universal appeal, the astronomy and astrophysics career field has had very little representation from minority populations.

In a study done by the American Astronomical Society, which includes most professionals and many students in these fields, only 21 percent of its members is female, which is light-years ahead of the representation of African Americans and Hispanics/Latinos--1 percent and 3 percent, respectively.

Not surprisingly, those numbers have prompted a call for diversity within the astro community.

In 2008, the National Science Foundation (NSF) started a program called Partnerships in Astronomy and Astrophysics Research and Education (PAARE, pronounced "pair"). Its goal was to identify and explore ways to repair "leaks" in the astronomy/astrophysics career pipeline for minority students. In many cases, minority students would start out studying astronomy, but they weren't making it all the way through the pipeline to pursue science careers.

When Bastien finished her undergraduate degree at the University of Maryland, she too wasn't sure whether she was appropriately prepared for the rigors of a grad school education in astronomy.

"I was petrified of grad school," she said. "I hadn't taken advantage of research opportunities as an undergrad largely due to personal challenges. But also because our department was so big, I fell between the cracks there."

PAARE aimed to make the face of astronomy more inclusive by seeing that minority students like Bastien got the right mix of resources, mentoring and encouragement. The partnership found that this required a multi-faceted approach that could target those pipeline points where "leaks" were most likely and "pair" some strong astronomy programs with schools that have more diverse populations, providing mentoring and support.

In Bastien's case, the PAARE Fisk-Vanderbilt Masters-to-Ph.D. Bridge Program proved to be one where she not only got her Ph.D., but had the opportunity to analyze stellar variability data, which led to a paper in Nature, being named a Hubble fellow and to her current postdoctoral work at Penn State.

The leaky pipeline

"We currently fund several highly complementary PAARE partnerships, which attack the leaky pipeline at different stages," said Dan Evans, the NSF program director who manages PAARE funding for the Division of Astronomical Sciences. "We're deeply concerned about the underrepresentation of minority students in astronomy and are massively proud of the successes of the students and staff who have participated in PAARE. We are exposing students to cutting-edge research. We are providing important new opportunities. And mentoring is utterly critical."

Though the partnerships target different points in the pipeline, they all emphasize mentoring, access to research opportunities and resources early on. They also emphasize an infrastructure that can address both academic and personal issues that might hinder progress.

"Queens is the most diverse county in the country," said Tim Paglione, director of AstroCom NYC, a partnership between astronomers at the City Universities of New York (CUNY), the American Museum of Natural History and Columbia University. Of the current PAARE partnerships, this is the only one that focuses exclusively on undergraduate students, targeting freshmen and sophomores. It also has the added challenge of CUNY being located throughout New York City, creating unique transportation issues that can deter students who feel inadequately prepared or supported.

That's why this program only accepts four new students each year. It supports students with summer fellowships, school scholarships, transportation stipends and program-provided laptops. It also provides long-term career mentors, research mentors, travel to observatories and professional meetings and membership in the American Astronomical Society.

"The problem is gigantic, but our astronomy field is also small," Paglione said. "That means even with our little program, we can have an impact. If we graduated two students each year from underrepresented groups who then went onto graduate school, we would be one of the leading programs in the country."

Keivan Stassun started a PAARE-like partnership even before PAARE existed, using funding from his NSF CAREER award in 2003 to develop the Fisk-Vanderbilt program, which focused on the potential pipeline leak at this juncture.

"That CAREER award gave me seed funding to do things like develop a website and recruit a couple of students as research assistants," Stassun said. "The CAREER grant got the whole thing going, both in terms of cash and caché as I got buy-in from both universities."

Broader than just astronomy, Stassun' s program has admitted 78 students in physics, biology, chemistry, materials science and astronomy, with the belief that they can impact these STEM disciplines as well. "This felt like the perfect program for me," Bastien recalled. "The extra encouragement helped. I was immediately working on real science--on rare eruptive young stars--because they serendipitously had these data they needed analyzed."

Another potential leak in this pipeline comes right after college, and South Carolina State University (SCSU) partnered with the NSF-funded National Optical Astronomy Observatory and Clemson University to address the loss of minority astronomy students at this stage of their education.

"We hoped to mirror Keivan's success at Vanderbilt," said Don Walter, who started the Partnership in Observational and Computational Astronomy, based on an undergraduate physics curriculum at SCSU. "We overestimated the number of students we'd get involved, so we haven't yet seen the numbers at the grad program that we hoped for, but the momentum is there, and we believe we have the right supports in place."

The SCSU partnership admittedly has had different obstacles and issues. It doesn't have full-time researchers because SCSU is a predominantly undergraduate school. The astrophysics portion of the curriculum is a concentration, not a degree. And the STEM graduate programs are a few hours away at Clemson, not nearby.

Mentoring makes the difference

"We try to spend a lot of time with our students as soon as possible. Because they don't take their first physics courses until their second year, it would be easy for them to get lost," Walter said. "I'll ask them to come by to make sure we connect early on--even waiting outside their classrooms if my emails don't bring them in. Students need early interaction."

This is a common theme throughout PAARE partnerships. Interaction with other students at the same and more advanced levels, as well as faculty, seems critical to success.

"We've added a number of mentoring layers," Stassun said about the Fisk-Vanderbilt program. "We assign to all incoming students a pair of peer mentors known as 'bridge buddies' who are students just one year ahead, and another mentor who is a few years further ahead. That way, they can see their future in front of them. We now also have a postdocs association, where the postdocs spend three-quarters of their time on their own research, but also a quarter of their time mentoring. They hold office hours, so students can talk to them, which offers a different perspective from faculty advisers."

At SCSU, one of the biggest challenges actually has been personal and financial problems that interfere with students staying in school.

"Some good students have had major personal or family issues," he said. "Money is tight, and many students find it too difficult to balance school life with demands in their personal lives. One female student in our physics program was an A-B student, but in the middle of the semester, her parents asked her to return home to care for a sick brother. She would have been a good undergraduate student and good graduate student."

Success determined by grit?

Interestingly enough, the admissions process for these PAARE partnerships has gone beyond evaluating just grades and test scores.

Stassun referred to a Nature article that he published this year with colleague Casey Miller about the Graduate Record Examination, or GRE, gender and ethnic bias that was discovered using published data from the Educational Testing Service that makes those tests. Their study found that women score approximately 80 points lower than men on the test's math section; and African Americans, approximately 200 points lower than Whites and Asians, on average.

For that reason, Stassun and his team put together a different set of metrics to measure something he refers to as "grit" or performance character.

"We found that the most successful students weren't necessarily the ones with the highest test scores," he said. "Graduate school is about persistence, so it makes sense to try and determine a candidate's capacity for being persistent. Consequently, we have achieved a very large, diverse program with a 90-percent Ph.D. persistence rate versus the national rate which is barely better than 50 percent." In other words, 90 percent of the students at Fisk-Vanderbilt are getting their doctoral degrees. He credits that success to careful, yet diverse selection and smart mentoring.

"PAARE funding makes a difference," Walter said. "In the August American Institute of Physics newsletter, SCSU was tied for eighth position nationally in terms of African American physics bachelors of science degree graduates during the five-year period, 2008-2012. We'd only graduated 12, but because the pool is so small, we're one of the top schools. PAARE helped us provide our students with meaningful internships at places like the National Optical Astronomy Observatory, which keeps their interest alive while giving them important experience."

Ariel Diaz, who attends the CUNY program, is a PAARE student who has benefitted from those experiences and demonstrated his "grit." A former Marine, he lives in New York City with his ailing father, whom he cares for. His astronomy interest was piqued in an introductory class that was far from the "easy A" he thought it would be. However, he found he really enjoyed the class, and Paglione's team recognized a student who had the wherewithal to succeed. Today, Diaz sifts through X-ray data from Chandra Observatory, looking for signals that could indicate black holes or other astronomical events.

"He's grown as a student. He's building a vision of himself in this career," Paglione said. "And honestly, that's what we want to do here. We want our students to see that future in themselves."

-- Ivy F. Kupec
Investigators
Donald Walter
Keivan Stassun
Timothy Paglione
Related Institutions/Organizations
Fisk University
CUNY York College
University of Texas at El Paso
South Carolina State University

SCIENTIST STUDY GENETIC DIVERSITY IN OCEAN MICROBES

FROM:  NATIONAL SCIENCE FOUNDATION
Octillions of microbes in the seas: Ocean microbes show incredible genetic diversity

In a few drops of seawater, one species, hundreds of subpopulations
The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacterial species essential to the marine ecosystem.

It's estimated that billions of the single-celled creatures live in the oceans, forming the center of the marine food web.

They occupy a range of ecological niches based on temperature, light, water chemistry and interactions with other species.

But the diversity within this single species remains a puzzle.

To probe this question, scientists at the Massachusetts Institute of Technology (MIT) recently performed a cell-by-cell genomic analysis of a wild population of Prochlorococcus living in a milliliter of ocean water--less than a quarter of a teaspoon--and found hundreds of distinct genetic subpopulations.

Each subpopulation in those few drops of water is characterized by a set of core gene alleles linked to a few associated flexible genes--a combination the scientists call the "genomic backbone."

This backbone gives the subpopulation a finely tuned ability to fill a particular ecological niche.

Diversity also exists within backbone subpopulations; most individual cells in the samples carried at least one set of flexible genes not found in any other cell in its subpopulation.

A report on the research by Sallie Chisholm and Nadav Kashtan at MIT, along with co-authors, appears in this week's issue of the journal Science.

The National Science Foundation (NSF), through its Divisions of Environmental Biology and Ocean Sciences, supported the research.

"In this extraordinary finding on the power of natural selection, the scientists have discovered a mosaic of genetically distinct populations of one of the most abundant organisms on Earth," says George Gilchrist, program director in NSF's Division of Environmental Biology.

"In spite of the constant mixing of the oceans," Gilchrist says, "variations in light, temperature and chemistry create unique habitats that evolution has filled with an enormous diversity of populations over millions of years."

Adds David Garrison, program director in NSF's Division of Ocean Sciences, "The results will change the way marine ecologists think about how planktonic microbes and, in turn, planktonic communities may respond to climate and environmental change."

The scientists estimate that the subpopulations diverged at least a few million years ago.

The backbone is an older, more slowly evolving, component of the genome, while the flexible genes reside in areas of the genome where gene exchange is relatively frequent, facilitating more rapid evolution.

The study also revealed that the relative abundance of the backbone subpopulations changes with the seasons at the study site near Bermuda, adding strength to the argument that each subpopulation is finely tuned for optimal growth under different conditions.

"The sheer enormity of diversity that must be in the octillion Prochlorococcus cells living in the seas is daunting to consider," Chisholm says. "It creates a robust and stable population in the face of environmental instability."

Ocean turbulence also plays a role in the evolution and diversity of Prochlorococcus.

A fluid mechanics model predicts that in typical ocean flow, just-divided daughter cells drift rapidly, placing them centimeters apart from one another in minutes, tens of meters apart in an hour, and kilometers apart in a week's time.

"The interesting question is, 'Why does such a diverse set of subpopulations exist?'" Kashtan says.

"The huge population size of Prochlorococcus suggests that this remarkable diversity and the way it is organized is not random, but is a masterpiece product of natural selection."

Chisholm and Kashtan say the evolutionary and ecological distinction among the subpopulations is probably common in other wild, free-living (not attached to particles or other organisms) bacteria species with large populations and highly mixed habitats.

Other co-authors of the paper are Sara Roggensack, Sébastien Rodrigue, Jessie Thompson, Steven Biller, Allison Coe, Huiming Ding, Roman Stocker and Michael Follows of MIT; Pekka Marttinen of the Helsinki Institute for Information Technology; Rex Malmstrom of the U.S. Department of Energy Joint Genome Institute and Ramunas Stepanauskas of the Bigelow Laboratory for Ocean Sciences.

The NSF Center for Microbial Oceanography, U.S. Department of Energy Genomics Science Program and the Gordon and Betty Moore Foundation Marine Microbiology Initiative also supported the work.

-NSF-

REMARKS BY FIRST LADY MICHELLE OBAMA AT STANFORD CENTER AT PEKING UNIVERSITY

FROM:   THE WHITE HOUSE  

Beijing, China

MRS. OBAMA:  (Applause.)  Thank you.  Well, ni-hao.  (Laughter.)  It is such a pleasure and an honor to be here with all of you at this great university, so thank you so much for having me.

Now, before I get started today, on behalf of myself and my husband, I just want to say a few very brief words about Malaysia Airlines Flight 370.  As my husband has said, the United States is offering as many resources as possible to assist in the search.  And please know that we are keeping all of the families and loved ones of those on this flight in our thoughts and prayers at this very difficult time.

Now with that, I want to start by recognizing our new Ambassador to China, Ambassador Baucus; President Wang; Chairman Zhu; Vice President Li; Director Cueller; Professor Oi, and the Stanford Center; President Sexton from New York University, which is an excellent study abroad program in Shanghai; and John Thornton, Director of the Global Leadership Program at Tsinghua University.  Thank you all for joining us.

But most of all, I want to thank all of the students who are here today.  And I particularly want to thank Eric Schaefer and Zhu Xuanhao for that extraordinary English and Chinese introduction.  That was a powerful symbol of everything that I want to talk with you about today.

See, by learning each other’s languages, and by showing such curiosity and respect for each other’s cultures, Mr. Schafer and Ms. Zhu and all of you are building bridges of understanding that will lead to so much more.  And I’m here today because I know that our future depends on connections like these among young people like you across the globe.

That’s why when my husband and I travel abroad, we don’t just visit palaces and parliaments and meet with heads of state.  We also come to schools like this one to meet with students like you, because we believe that relationships between nations aren’t just about relationships between governments or leaders -- they’re about relationships between people, particularly young people.  So we view study abroad programs not just as an educational opportunity for students, but also as a vital part of America’s foreign policy.

Through the wonders of modern technology, our world is more connected than ever before.  Ideas can cross oceans with the click of a button.  Companies can do business and compete with companies across the globe.  And we can text, email, Skype with people on every continent.

So studying abroad isn’t just a fun way to spend a semester; it is quickly becoming the key to success in our global economy.  Because getting ahead in today’s workplaces isn’t just about getting good grades or test scores in school, which are important.  It’s also about having real experience with the world beyond your borders –- experience with languages, cultures and societies very different from your own.  Or, as the Chinese saying goes:  “It is better to travel ten thousand miles than to read ten thousand books.”

But let’s be clear, studying abroad is about so much more than improving your own future.  It’s also about shaping the future of your countries and of the world we all share.  Because when it comes to the defining challenges of our time -– whether it’s climate change or economic opportunity or the spread of nuclear weapons -- these are shared challenges.  And no one country can confront them alone.  The only way forward is together.

That’s why it is so important for young people like you to live and study in each other’s countries, because that’s how you develop that habit of cooperation.  You do it by immersing yourself in one another’s culture, by learning each other’s stories, by getting past the stereotypes and misconceptions that too often divide us.

That’s how you come to understand how much we all share.  That’s how you realize that we all have a stake in each other’s success -- that cures discovered here in Beijing could save lives in America, that clean energy technologies from Silicon Valley in California could improve the environment here in China, that the architecture of an ancient temple in Xi’an could inspire the design of new buildings in Dallas or Detroit.  

And that’s when the connections you make as classmates or labmates can blossom into something more.  That’s what happened when Abigail Coplin became an American Fulbright Scholar here at Peking University.  She and her colleagues published papers together in top science journals, and they built research partnerships that lasted long after they returned to their home countries.  And Professor Niu Ke from Peking University was a Fulbright Scholarship -- Scholar in the U.S. last year, and he reported -- and this is a quote from him -- he said, “The most memorable experiences were with my American friends.”

These lasting bonds represent the true value of studying abroad.  And I am thrilled that more and more students are getting this opportunity.  As you’ve heard, China is currently the fifth most popular destination for Americans studying abroad, and today, the highest number of exchange students in the U.S. are from China.

But still, too many students never have this chance, and some that do are hesitant to take it.  They may feel like studying abroad is only for wealthy students or students from certain kinds of universities.  Or they may think to themselves, well, that sounds fun but how will it be useful in my life?  And believe me, I understand where these young people are coming from because I felt the same way back when I was in college.

See, I came from a working-class family, and it never occurred to me to study abroad -- never.  My parents didn’t get a chance to attend college, so I was focused on getting into a university, earning my degree so that I could get a good job to support myself and help my family.  And I know for a lot of young people like me who are struggling to afford a regular semester of school, paying for plane tickets or living expenses halfway around the world just isn’t possible.  And that’s not acceptable, because study abroad shouldn’t just be for students from certain backgrounds.

Our hope is to build connections between people of all races and socioeconomic backgrounds, because it is that diversity that truly will change the face of our relationships.  So we believe that diversity makes our country vibrant and strong.  And our study abroad programs should reflect the true spirit of America to the world.

And that’s why when my husband visited China back in 2009, he announced the 100,000 Strong initiative to increase the number and diversity of American students studying in China.  And this year, as we mark the 35th anniversary of the normalization of relationships between our two countries, the U.S. government actually supports more American students in China than in any other country in the world.

We are sending high school, college and graduate students here to study Chinese.  We’re inviting teachers from China to teach Mandarin in American schools.  We’re providing free online advising for students in China who want to study in the U.S.  And the U.S.-China Fulbright program is still going strong with more than 3,000 alumni.

And the private sector is stepping up as well.  For example, Steve Schwarzman, who is the head of an American company called Blackstone, is funding a new program at Tsinghua University modeled on the Rhodes Scholarship.  And today, students from all kinds of backgrounds are studying here in China.

Take the example of Royale Nicholson, who’s from Cleveland, Ohio.  She attends New York University’s program in Shanghai.  Now, like me, Royale is a first-generation college student.  And her mother worked two full-time jobs while her father worked nights to support their family.  And of her experience in Shanghai, Royale said -- and this is her quote -- she said, “This city oozes persistence and inspires me to accomplish all that I can.”  And happy birthday, Royale.  It was her birthday yesterday.  (Laughter.)

And then there’s Philmon Haile from the University of Washington, whose family came to the U.S. as refugees from Eritrea when he was a child.  And of his experience studying in China, he said, “Study abroad is a powerful vehicle for people-to-people exchange as we move into a new era of citizen diplomacy.”

“A new era of citizen diplomacy.”  I could not have said it better myself, because that’s really what I’m talking about.  I am talking about ordinary citizens reaching out to the world.  And as I always tell young people back in America, you don’t need to get on a plane to be a citizen diplomat.  I tell them that if you have an Internet connection in your home, school, or library, within seconds you can be transported anywhere in the world and meet people on every continent.

And that’s why I’m posting a daily travel blog with videos and photos of my experiences here in China, because I want young people in America to be part of this visit.  And that’s really the power of technology –- how it can open up the entire world and expose us to ideas and innovations we never could have imagined.

And that’s why it’s so important for information and ideas to flow freely over the Internet and through the media, because that’s how we discover the truth.  That’s how we learn what’s really happening in our communities and our country and our world.  And that’s how we decide which values and ideas we think are best –- by questioning and debating them vigorously, by listening to all sides of an argument, and by judging for ourselves.

And believe me, I know how this can be a messy and frustrating process.  My husband and I are on the receiving end of plenty of questioning and criticism from our media and our fellow citizens.  And it’s not always easy, but we wouldn’t trade it for anything in the world.  Because time and again, we have seen that countries are stronger and more prosperous when the voices of and opinions of all their citizens can be heard.

And as my husband has said, we respect the uniqueness of other cultures and societies, but when it comes to expressing yourself freely and worshipping as you choose and having open access to information, we believe those universal rights -- they are universal rights that are the birthright of every person on this planet.  We believe that all people deserve the opportunity to fulfill their highest potential as I was able to do in the United States.

And as you learn about new cultures and form new friendships during your time here in China and in the United States, all of you are the living, breathing embodiment of those values.  So I guarantee you that in studying abroad, you’re not just changing your own life, you are changing the lives of everyone you meet.

And as the great American President John F. Kennedy once said about foreign students studying in the U.S., he said “I think they teach more than they learn.”  And that is just as true of young Americans who study abroad.  All of you are America’s best face, and China’s best face, to the world -- you truly are.

Every day, you show the world your countries’ energy and creativity and optimism and unwavering belief in the future.  And every day, you remind us -- and me in particular -- of just how much we can achieve if we reach across borders, and learn to see ourselves in each other, and confront our shared challenges with shared resolve.

So I hope you all will keep seeking these kinds of experiences.  And I hope you’ll keep teaching each other, and learning from each other, and building bonds of friendship that will enrich your lives and enrich our world for decades to come.

You all have so much to offer, and I cannot wait to see all that you achieve together in the years ahead.

Thank you so much.  Xie-Xie.  (Applause.)

 END                11:48 A.M. CST  

YELLOWSTONE ECOSYSTEM: NATURAL RELATIONSHIPS

Photo:  Yellowstone Beaver.  Credit: National Park Service.

FROM: NATIONAL SCIENCE FOUNDATION
Yellowstone Ecosystem Needs Wolves and Willows, Elk and...Beavers?
Scientists plot crucial links among Yellowstone plant and animal species

Wolves and Yellowstone. In the public mind, and in nature, the two are inextricably linked.

Now, it turns out, they aren't alone on the ecological dance floor.

Elk and willows play a critical role in wolves' success in the Yellowstone ecosystem, willows serving as browse for elk--and elk as food for wolves.

But there's another species involved, one that's instrumental to these well-choreographed steps: the beaver.

"Beavers are the missing piece in this ecosystem," says ecologist Tom Hobbs of Colorado State University (CSU) in Fort Collins.

No wolves, no beavers

The loss of wolves caused far-reaching changes in the Yellowstone ecosystem: more elk and fewer willows. With no willows to slow stream flow, creeks flowed faster and faster. Beavers prefer slow-moving waters, so they disappeared with the willows.

"Putting wolves back isn't enough to reverse the extensive changes caused by their long absence," Hobbs and other scientists discovered in a decade-long research project.

The ecologists published results of their study this week in the journal Proceedings of the Royal Society B. In addition to Hobbs, co-authors are Kristin Marshall, formerly of CSU and now of the National Oceanic and Atmospheric Administration, and David Cooper of CSU. Marshall is the paper's lead author.

"This research illustrates the value of long-term ecological experiments to understanding how species interactions cascade through food webs to determine ecosystem resilience," says Alan Tessier, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research.

"The results have immediate practical applications in restoring and protecting ecosystems such as that of Yellowstone."

Wolves aren't enough

Scientists had thought that the return of the wolf, leading to a cutback on elk numbers and willow-browsing, was central to restoring the Yellowstone ecosystem. "But Yellowstone also needs beavers," says Hobbs.

That's why bringing back wolves didn't work to quickly restore the ecosystem, the researchers believe.

Wolves hunted elk and brought down numbers of these ungulates. But removing elk-browsing wasn't enough for the willows. They needed the sluggish streams created by beavers. But the beavers were gone.

Streams: the missing link

Once, beavers had been abundant anywhere streams flowed through Yellowstone. And that was almost everywhere.

In the past, dams made by beavers were ubiquitous features of Yellowstone's stream network. A third of mainstream reaches show evidence of sediment deposition as a result of beaver dams, a process that's happened for millennia. That sediment offered willows a place to take root.

In the spring of 1921, scientist Edward Warren of the Roosevelt Wild Life Forest Experiment Station in Syracuse, N. Y., conducted a study of beavers in Yellowstone. Warren found beavers and their ponds scattered throughout the park.

Near the Elk Creek Bench Colony, for example, Warren spotted "a group of beaver ponds which present interesting features," he stated in a report published in the 1920s.

"The water supply is a small brook originating from springs in a boggy tract of several acres. The brook flows through a flat depression in a ridge, and it is in the swampy, springy ground just below the woods that most of the ponds are located."

It's a rare if not non-existent sight in Yellowstone today, especially on the park's northern range where Hobbs' team conducted its research.

"Excessive browsing of willows [by elk after wolves were gone] was implicated in the disappearance of beavers from streams during the twentieth century," Marshall, Hobbs and Cooper write in their paper. "The loss of beaver ponds from the stream network...compressed the area of bare, moist substrate needed for willow establishment."

Yellowstone ecosystem questions: answered by beavers?

Restoring an ecologically complete ecosystem in Yellowstone requires the return of willows--and with them, beavers.

There's a clear threshold for ecosystem recovery. Willow stands must be more than six feet tall, the scientists found. That height is important, says Marshall. Then willows are beyond the reach of browsing elk, and can serve as seed sources for new young willows.

Once willows have returned, beavers will gnaw down a certain number of them to build dams. The dams will further slow stream flow, allowing yet more willows to grow.

The results offer new insights on the role of wolf-driven trophic cascades in the Yellowstone ecosystem, says Hobbs.

Trophic cascades like that in Yellowstone occur when predators--or the lack thereof--in an ecosystem change the abundance or alter traits of their prey, in turn affecting the next lower trophic level.

"The reintroduction of wolves to Yellowstone has contributed to improvements in the park's ecology, but clearly that ecology is a complicated one," says Marshall. "The take-home message is that we have to be careful not to remove predators in the first place."

U.S. SECRETARY OF LABOR SOLIS MAKES STATEMENT ON 2012 INTERNATIONAL DAY OF PERSONS WITH DISABILITIES

U.S. Secretary Of Labor Hilda L. Solis

FROM: U.S. DEPARTMENT OF LABOR

Statement by Secretary of Labor Hilda L. Solis on 2012 International Day of Persons with Disabilities

WASHINGTON —December 3, 2012
Secretary of Labor Hilda L. Solis issued the following statement to mark the 2012 International Day of Persons with Disabilities:

"Today is an important opportunity to celebrate the diversity and innovation that people with disabilities bring to businesses of all sizes in all industries every day. Through their talents and skills, they are contributing to global economic growth and making the United States a stronger nation.

"More countries are coming to recognize the importance of giving all qualified job seekers equal opportunity to compete. However, in both good economic times and in bad, people with disabilities continue to have fewer opportunities in our educational institutions and workplaces than those without disabilities. This must change. We know that there’s a strong business case for why companies should hire people with disabilities. These Americans want to work, and they’re highly capable of success if proper accommodations are made. In fact, there’s a growing body of evidence proving that workers with disabilities often meet or exceed the job performance of those without them.

"Here at home, we’ve made tremendous advances since the passage of the Americans with Disabilities Act in combating discrimination against those who may have a disability. With this progress domestically comes a greater responsibility on the world stage to work with other nations so that they embrace policies to help the world’s 1 billion persons with disabilities access good jobs, educational opportunities and critical medical care.

"Today, I join President Obama in calling on foreign nations to recognize the dignity and extraordinary talents of persons with disabilities everywhere. The Department of Labor is committed to providing our partners at home and abroad with information about the most effective strategies for employing persons with disabilities."