Sunday, November 18, 2012

New Home for the Visionlearning Blog

This blog is officially obsolete!  Find us at our new location:
Dear Readers,

We're excited to announce that the Visionlearning blog has moved to a new home on the main Visionlearning site.  We've got a new address and a new look, but we'll still be working hard to bring you interesting STEM and education posts, including:
In our new location, it will be easier than ever to access Visionlearning modules in disciplines from biology to physics, as well as our science glossary with hundreds of definitions of terms used in STEM disciplines.

We hope you'll join us in our new location -- To make sure you stay up to date, you can subscribe to receive new posts by email or RSS feed once you get there. We will not be maintaining this blog anymore, so please make sure you update your bookmarks, news readers, and other sources you use to find news and information.

As always, we would love to hear your thoughts on the new layout, the topics we're posting about, or any ways we can make the Visionlearning Blog better.  Thanks for reading!

Friday, November 9, 2012

Image of the Week: How to Look Inside a Fish

Scientists Sandra Raredon and Lynne Parenti at Smithsonian's National Museum of Natural History use
x-rays to get an inside look at fishes like these Lookdowns (Selene vomer).
Image courtesy: Smithsonian's National Museum of Natural History

Scientists use all sorts of visuals to study the natural world, including graphs, maps and photographs. But some of the most beautiful scientific visuals have to be the fish x-rays taken by Sandra Raredon and Lynne Parenti, ichthyologists (scientists who study fish) at Smithsonian's National Museum of Natural History.  Our image of the week is an x-ray showing three lookdowns (Selene vomer), silvery fish with a permanent "scowl" found mainly in warm waters of the western Atlantic.

The Smithsonian's fish collection contains about four million specimens, representing approximately 70 percent of the world's fish diversity, and Raredon and Parenti can study these specimens without having to dissect or otherwise damage them.  Their images help unravel the long history of fish evolution using clues, such as the number of vertebrae and positioning of fins, that are easily visible in x-rays.

Learn about how scientists use this technique and what they are learning from it on the Smithsonian National Museum of Natural History's exhibit page X-Ray Vision: Fish Inside Out.

Browse more of these beautiful x-rays on the NMNH Flickr page.

Learn about how visual data, whether x-rays or topographic maps, help scientists explore all kinds of topics in our module Data: Using Graphs and Visual Data.

Wednesday, November 7, 2012

Tragedies in Science: The Collapse of the Tacoma Narrows Bridge

Since it's collapse in 1940, the Tacoma Narrows
Bridge has been rebuilt, this time as a
twin suspension bridge. Image courtesy: WSDOT (Flickr CC)
When you think of iconic bridges of the world, the Tacoma Narrows Bridge, which spans a narrow strait in the Puget Sound south of Seattle, may not come to mind immediately.  But that bridge (today it's actually a set of twin bridges--one for each direction of traffic) has an incredible history that serves as a serious cautionary tale for engineers.

The original Tacoma Narrows bridge, completed in 1940, was a long time in the making but short-lived once it was finally built. The idea of building a bridge across the sound to connect the city of Tacoma to the Kitsap Peninsula dates back to at least 1889.  During the 1920s and 30s a number of citizen campaigns and leaders supported various designs and approaches to building a bridge

One of the major sticking points for all of these efforts was the cost. In 1938, the state of Washington applied for federal funding to build the bridge. The state bridge engineer, Clark Eldridge, drew up a fairly standard suspension bridge design with an estimated price tag of $11 million, but officials were skeptical that a project of that magnitude could pay for itself in bridge tolls.  In the end, they granted the state $6.4 million and required them to hire Leon Moisseiff, a bridge engineer from New York who said the bridge could be built for much less than $11 million.

Moisseff's plan was indeed much less expensive because his design used far less steel and called for the Tacoma Narrows Bridge to be very light and narrow compared to other suspension bridges of the time. When they saw the plan, engineers at the Washington State Highway Department protested, calling the bridge design "fundamentally unsound."  But that did not stop the project.  Construction began on November 23, 1938.

During construction, workers noticed that the bridge bounced.  Soon after opening in July 1940, the bridge became known by engineers and motorists alike for "the bounce" or "the ripple."  It was rated to withstand winds up to 120 miles per hour, but even in a light breeze the bridge moved.  Motorists reported waves, sometimes up to 5 feet tall, undulating from one end of the bridge to the other.  Sometimes the bouncing was short-lived, but on occasion it was reported to last for up to six hours. The bridge earned the nickname Galloping Gertie.  Some locals steered clear of Gertie out of fear or to avoid sea sickness; others sought it out as a thrill ride.

In the spring of 1940, the Toll Bridge Authority contacted Moisseiff who reported that two of his other recent bridges were having similar movement issues, but at a smaller scale. The Authority then hired engineering professor F. Bert Farquharson from the University of Washington to find a solution to the problem.  Farquharson and his students built scale models of the bridge and conducted wind tunnel experiments.  In October, engineers added temporary tie-down cables to anchor the bridge to the seafloor and diagonal cables between the bridge's deck and the main cables to brace it.  This helped limit the bridge's movement, but not enough.

In early November, as workers repaired one of the tie-down cables that had broken loose from Gertie's galloping, Farquharson completed his wind tunnel studies.  He noted a torsional (twisting) motion in the bridge model under high wind conditions.  "We watched it," Farquharson later told reporters, "and we said that if that sort of motion ever occurred on the real bridge, it would be the end of the bridge."

Guided by Farquharson's findings, the Toll Bridge Authority began drawing up a contract to have wind deflectors installed on the bridge. The morning of November 7, the state bridge engineer, Clark Eldridge was sketching plans for the deflectors, pricing materials, and preparing a rapid response that would have had the entire bridge covered in wind deflectors within 45 days. But they were too late.

By 7:30 am, 42-mile-per-hour winds were rushing up the Narrows from the Southwest and hitting Gertie broadside.  She began to gallop. Farquharson, Eldridge, and a crowd of spectators began to gather, photographing and even taking video of the bridge.  At 10:03 am, the bridge suddenly began the lateral twisting motion that Farquharson had feared.  Pieces of concrete from the roadway began to break free, and at 11:02 am, a 600-foot span collapsed into the sound.  Galloping Gertie had failed.

Footage from the Nov 7, 1940 collapse of the Tacoma Narrows Bridge. Courtesy: Internet Archives

Fortunately, no humans and only one dog died during the collapse, but the outcome could have easily been much worse.  In a situation like this who is to blame?  Did the collapse of the bridge result from an ethical breach or an honest miscalculation?  Does the designer of the bridge bear responsibility?  What about the federal officials who put construction costs above other considerations--including perhaps safety--when selecting a design and funding the project?

Answers to ethical questions like these are not always straightforward.  Fortunately, though, there are standards of conduct and general principles that members of the scientific community abide by.  You're probably familiar with the Hippocratic Oath that doctors take, declaring that (among other things) they vow to do no harm to their patients.  In the U.S., the National Society of Professional Engineers' code of ethics declares that engineers shall "hold paramount the safety, health and welfare of the public." General standards relating to scientific methods and to topics of study (especially human and animal subjects) also guide researchers.

So what if Clark Eldridge's original (more expensive) design had been built instead of Leon Moisseiff's lighter, cheaper version?  Structural engineers who reviewed the original plans for the State of Washington concluded that the bridge would likely still be standing.

For more about ethical standards and dilemmas in science and engineering, read our Scientific Ethics module.

For more about how models of all types are used in research, visit our module Research Methods: Modeling.

For more about the history and design of the Tacoma Narrows Bridge (and other suspension bridges), check out the Washington State Department of Transportation's More Than a Bridge site.

Friday, October 12, 2012

Image of the Week: Le Grand K of the Metric System

"Le Grand K," a cylindrical weight made of platinum and iridium that serves as the
international prototype of the kilogram, is kept in a vault in France.
Image: Bureau International des Poids et Mesures

In honor of National Metric Week (which wraps up tomorrow), our image of the week shows "Le Grand K," a cylindrical weight that is the international standard barer for the kilogram.  Made of platinum and iridium and created in 1889, this special weight literally defines the mass of a kilogram. There are six official copies held at the Bureau International des Poids et Mesures (International Bureau of Weights and Measures) and a number of other copies around the world that serve as the national standard for the kilogram in their home countries.

The kilogram is the only metric measurement that is still defined by a physical object, rather than a universal physical constant. (A meter, for example, used to have a platinum-iridium standard as well but is now defined as the distance that light travels in a vacuum in 1/299,792,458 of a second.)  In recent years, scientist have determined that Le Grand K is losing small amounts of mass, and some have been advocating for a new kilogram standard that is based on a physical constant.

Check out our module on the Metric System to learn more about the various metric units and how scientific notation helps us describe things that are very large or very small

Visit the Bureau International des Poids et Mesures to read more about the International Prototype for the Kilogram

Monday, October 8, 2012

Five Inspiring Hispanic Scientists

One of many inspiring Hispanic scientists: Dr. Helen
Rodriguez-Trias, physician, educator, and advocate
for women's health and equal access to medical.
care. Image Courtesy: National Library of Medicine
The U.S. Census Bureau estimates that the Hispanic population in the U.S. will reach 132.8 million (or 30 percent of the total U.S. population) by the year 2050.   But Hispanic students (as well as other minorities) continue to be underrepresented in the STEM disciplines and to receive STEM degrees at a lower rate than their White counterparts. In K-12 education, Hispanic students are more likely than Whites to be exposed to funding inequities and to have science teachers who did not major in science.

In the face of these disparities and in honor of National Hispanic Heritage Month, we're highlighting five Hispanic scientists that have had a major and lasting impact on the world around them.   In many cases they overcame obstacles, including racism and sexism, poverty, cultural and family expectations, and lack of mathematics background, in order to work and excel in the fields that they love.  Our hats are off to all of them, and to anyone out there who is studying or working in a STEM field.  May these stories inspire you.

Dr. Helen Rodriguez-Trias (1929 - 2001)
"We cannot achieve a healthier us without achieving a healthier, more equitable health care system, and ultimately, a more equitable society."

Helen Rodiriguez-Trias combined the two things she loved most--science and people--by pursuing a career in medicine. Born in New York city in 1929, Rodiriguez-Trias moved back and forth between New York and her parents' native Puerto Rico during her childhood and early career.  She graduated from the University of Puerto Rico Medical School in 1960 and established the island's first center for the care of newborn babies, which dramatically lowered the death rate for newborns at the hospital where she completed her residency.

In 1970, she moved back to New York where she became head of the pediatrics department at Lincoln Hospital in the South Bronx.  In addition to her work as a physician, Rodiriguez-Trias fought to improve medical care for people who had limited access due to poverty, cultural and language barriers, and discrimination. Among her many leadership roles, Rodiriguez-Trias served as the (first Latina) president of the American Public Health Association and the medical director of the New York State AIDS Institute. She also became a tireless advocate and leader in the women's health movement, fighting for equal access to healthcare for poor women and children and fighting against the horrifying practice of forced sterilization. In 2001, less than a year after receiving the Presidential Citizen's Medal, Helen Rodriguez-Trias succumbed to cancer.

For more, visit the National Library of Medicine and the American Journal of Public Health

Dr. Francisco Dallmeier (1953 - )
"In this century we will make the final decisions about how this sixth species extinction currently in progress will end… It is a tremendous responsibility."

At a very young age, Francisco Dallmeier knew that he wanted to follow in his great-grandfather's footsteps and make a career out of working with plants and animals.  At 14, he began volunteering at the La Salle Museum of Natural History in his hometown of Caracas, Venezuela.  He moved up the ranks with remarkable speed, and by age 20, he was appointed director of the museum.  At the same time, he was working toward a biology degree at the Central University of Venezuela, and he eventually moved to the United States to pursue a masters and then a Ph.D. in wildlife ecology at Colorado State University. 

From Colorado, Dallmeier went to Washington, DC to work at the Smithsonian Institution.  As the head of the Smithsonian's Monitoring and Assessment of Biodiversity (MAB) program, he has developed important and widely-recognized techniques for measuring and tracking changes in biodiversity. Dallmeier has worked all over the world in places as far reaching as Gabon and Peru focusing on ways to help environmental advocates and industry work together to reduce the impacts of human development.  MAB now has more than 300 research plots and trains scientists around the world in the tools and techniques of conservation biology.

For more, visit the Smithsonian Conservation Biology Institute and the Friends of the National Zoo

Ynes Mexia (1870-1938)
Ynes Mexia found her true passions--botany and exploring--a bit later in life.  The daughter of a Mexican diplomat and an American socialite, Mexia was born in Washington, DC in 1870.  She made her first career as a social worker, and it wasn't until age 51 that she began taking classes in botany at the University of California at Berkeley. In 1925, she joined a botanical collecting expedition to Mexico sponsored by Stanford University but decided to break off from the group to collect on her own.  She returned with more than 1,500 plant specimens, but that was only the beginning.

Mexia went on to conduct collecting expeditions (often solo) in Alaska, the western U.S., Mexico, and South America, including a 4,800-kilometer canoe trip along the Amazon River. During her last expedition to Mexico, she became ill and was diagnosed with lung cancer. She died in 1938 shortly after her diagnosis.  Mexia's career in botany was short, but her contribution was large: in 13 years of work she collected nearly 150,000 specimens.  Among those, roughly 500 were new species, and two were new genera.

For more, visit JSTOR Plant Science and the UC Berkeley Jepson Herbaria

Dr. Ellen Ochoa (1958 - )
As a child growing up in La Mesa, CA, Ellen Ochoa loved math and music.  She earned her undergraduate degree in physics from San Diego State University, and was contemplating a career in business or as a classical flutist. In the end, she decided to go to graduate school for electrical engineering at Stanford University. In 1983, two years before Ochoa completed her Ph.D., Sally Ride, the first American woman in space, made her first shuttle mission.  Ochoa was inspired, in part by Ride, to apply for the astronaut program.  She was accepted and became an astronaut 1991.  She would soon become the first Latina to go to space.

Since then, Ochoa has logged 978 hours in space, earned three patents, and held a slew of leadership posts at NASA that include assignments on four space missions (at least one of which involved a flute recital in space).  Ochoa now serves as Deputy Director of the Johnson Space Center and has received many awards for her work as an engineer, physicist, astronaut, and leader.  She has also traveled around the country sharing her experiences with students in the hopes that they will be inspired to dream big and follow their passions.

For more, visit Latina Women of NASA, the Lemelson-MIT Inventor Archive, and NASA News

Dr. Mario Molina (1943 - )
"I am heartened and humbled that I was able to do something that not only contributed to our understanding of atmospheric chemistry, but also had a profound impact on the global environment."

By age 11, Mario Molina had already decided that he wanted to be a research chemist.  Born in Mexico City in 1943, Molina was hooked on science the first time he peered through a microscope and saw tiny amoebas swimming around. He converted a little-used bathroom in his family's home to a chemistry lab, and, with the help of an aunt who was a chemist, began conducting chemistry experiments appropriate for college freshmen. After attending boarding school in Germany, Molina returned to Mexico to study chemical engineering at Universidad Nacional Autónoma de México (UNAM).  When he graduated, Molina knew he wanted to pursue a Ph.D. in physical chemistry, but he also knew his math and physics skills would be behind other students who had majored in physical chemistry.  He did some graduate coursework in Germany, spent several months studying math on his own, and taught at UNAM before eventually applying to get his doctorate at University of California at Berkeley.

With his Ph.D. in hand, Molina went to work in the lab of F. Sherwood Rowland at the University of California at Irvine. There, he began studying what happens to a class of nonreactive chemicals called chlorofluorocarbons, or CFC's, when they are released into the air.  Molina and Rowland quickly realized that when the sun breaks down CFC's in the upper atmosphere, the chlorine atoms released catalyze a reaction that destroys ozone molecules. That reaction, repeated over and over again, would eventually deplete and lead to thin spots in the Earth's protective layer of ozone.  This realization, combined with work by another scientist named Paul J. Crutzen who was studying the ozone layer over Antarctica, eventually led to a global ban on CFC's--and to the 1995 Nobel Prize in Chemistry for the three researchers.

For more, visit the Nobel Prize Foundation

These are just a handful of the many, many inspiring stories out there, and it was extremely difficult to pick five.  Please share your thoughts with us: which Hispanic scientist(s) do you find most inspiring?

If you are interested in learning more about these and other Hispanic leaders in science, check out these resources.

Society for the Advancement of Chicanos and Native Americans in Science

SACNAS Biography Project

The Society of Mexican American Engineers and Scientists (MAES)

SHPE Foundation (Advancing Hispanic Excellence in Technology, Engineering, Math, and Science)

Latinos in Science, Math, and Professions by David E. Newton (book)

Monday, October 1, 2012

Vote! Help Us Rename One of Our Module Collections

We want your input!  Help us rename our collection of modules that includes profiles of scientists at work and case studies of intriguing experiments and discoveries. They include modules like "Studying Climate Change with Kevin Arrigo" and "From Stable Chromosomes to Jumping Genes with Barbara McClintock."

Which name do you like best?

Got another suggestion?  Share it in the comments below.  Thanks!

Thursday, September 27, 2012

Video of the Week: A Tribute to Rachel Carson and Silent Spring

"Over increasingly large areas of the United States spring now comes unheralded by the return of birds, and the early mornings are strangely silent where once they were filled with the beauty of bird song." 
-- Rachel Carson, Silent Spring 1962 

Fifty years ago this week, Rachel Carson's now-famous book Silent Spring rolled off of the presses. It drew widespread attention to the effects of pesticides like DDT on wildlife and human communities and is often credited with launching the modern environmental movement in the United States. The title laments the loss of songbirds to unintentional poisoning.

As a child growing up on a farm in Western Pennsylvania, Carson learned to love and respect birds and other wildlife. Our video of the week is a tribute to Carson and her enormous impact on public understanding of ecology and environmental toxicology in the United States. The Eastern Towhee shown here is one of many birds Carson likely heard singing on her farm during her formative years.  Thanks in large part to Carson's eye-opening book, broad applications of pesticides have been reduced, and there's hope that we will never experience a truly silent spring.

Read a brief biography of Rachel Carson and excerpts from her often lyrical writings

Learn more about the Eastern Towhee (including listening to other audio clips of their songs and calls) as well as many other bird species on the Cornell Lab of Ornithology's All About Birds site

Read the first chapter of Lind Lear's Rachel Carson: Witness for Nature, a detailed biography of Carson's life

Have you read Silent Spring or other writings by Rachel Carson? What did you think?