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.


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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

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?


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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)

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!

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.

LEARN MORE
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?

Tragedies in Science: The Crash of the Mars Climate Orbiter

In science, as in the rest of life, things don't always go as planned. From time to time, accidents, mistakes, and tragedies happen. In the worst cases, these experiences result in serious losses or even catastrophes that can affect many people. In less severe cases they are the painful (and sometimes expensive) blunders that we can eventually look back and laugh about.

But in almost every case--whether caused by bad luck, bad planning, lack of understanding, simple human error, or systemic problems in a research team or a society--there is something to be learned from these experiences. Always double check your unit conversions. Train your field crew for the harshest possible conditions and the worst case scenario. Recognize your colleagues and their contributions before it's too late.

The tragedies of science often don't appear in text books or journal articles, but they are just as much a part of science as any discovery or triumph. And, as you'll see in the first installment of our new Tragedies in Science blog series, even "rocket scientists" make mistakes. By taking a closer look at some of the accidents and tragedies of the past, we can find both practical lessons for the future and inspiration for how to persevere and learn from tragedy.


The Crash of the Mars Climate Orbiter 

An artist's concept showing NASA's Mars Climate Orbiter, which was
lost due to a unit conversion error 13 years ago. Image courtesy: NASA/JPL

September 23, 1999 should have been a day of excitement and celebration for researchers and science enthusiasts everywhere. That was the date--13 years ago this Sunday--that NASA's Mars Climate Orbiter was supposed to claim its spot in orbit around the Red Planet, roughly 180 km above the Martian surface. From that vantage point, the Orbiter would monitor conditions and send information back to Earth as part of the Mars Surveyor Program, which launched a series of missions in the 1990's and 2000's to study one of our closest neighbors in the solar system.

But the $125 million Orbiter was doomed.

As the spacecraft neared its destination, the engineers at NASA's Jet Propulsion Laboratory who were guiding the Orbiter thought everything was on target. Then, when the craft made it's final maneuvers to enter orbit, they lost communications. Something was wrong.

By examining data from the previous eight hours of the Orbiter's journey, NASA realized that the craft's approach had been much lower than intended--about 60 km above the planet's surface instead of 150 to 180 km. The altered course meant a rough ride through the Martian atmosphere that the Orbiter was not designed to withstand. The following day, the engineers concluded that the spacecraft had not survived the miscalculation, and the search for the Orbiter was abandoned.

Within a week of the accident, two committees (one internal and one composed of outside experts) had been formed to investigate what had gone wrong. They concluded that a simple mathematical and communications error was at the heart of the problem: one part of the mission team had used English units while the another part of the team had used metric units when making calculations related to the jet thrusters used to correct the Orbiter's trajectory during it's journey. A flubbed unit conversion had cost them a $125 million spacecraft, years of work, and untold scientific knowledge.

Luckily, unit conversion errors are an easy problem to fix, and you can bet NASA won't be repeating that mistake. In a statement released shortly after the crash, Dr. Edward Weiler, NASA's Associate Administrator for Space Science, said: "The problem here was not the error, it was the failure of NASA's systems engineering, and the checks and balances in our processes to detect the error. That's why we lost the spacecraft."
 

LEARN MORE 
Check out our Unit Conversion module for more about the Orbiter's demise and a primer on how to avoid a mistake like NASA's.

See Time's picks for the "Top 10 NASA Flubs."
 
And please let us know what you think of the first installment and the series as a whole! We are also always on the lookout for other tragic stories in science, so please share your ideas.

Image of the Week: Printing Blood Vessels and a Whole Lot More

In a paper published this week in the journal Advanced Materials, Dr. Shaochen Chen
demonstrated that blood vessels, which could eventually be used in artificial tissue, can be
created using a new 3D printing technique called dynamic optical projection stereolithography.   
Image courtesy: Biomedical Nanotechnology Laboratory, Chen Research Group, UC San Diego Jacobs School of Engineering

Do you have a good printer at home?  What about one that can print you a new car part, a toy, or another 3D object?  It may sound bizarre, but 3D printing (also known as additive manufacturing because a printer typically builds an object by slowly adding layers of material) is becoming more common in a wide range of contexts, including the battlefield and the medical field.

Our image of the week shows artificial blood vessels printed by researchers in the Biomeidcal Nanoengineering Lab at US San Diego.  Their technique uses light to trigger the formation of a solid 3D structure from a solution containing cells and biomolecules that are photo-sensitive (or reactive to light).  By carefully controlling the beam of light with a series of mirrors, they are able to fabricate tiny, intricate structures like those found in nature.  They believe the new process will lead to better tools for growing cells in the lab and could eventually even allow medical professionals to print tissues for regenerative medicine.

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Watch an amazing video and read about another application of 3D printing that was recently in the news: a bald eagle named Beauty was given a prosthetic beak made on a 3D printer after being injured by a gunshot. (Warning: although there's a happy ending, images may not be suitable for sensitive readers and viewers.)

Read the Science Insider piece about the newly created National Additive Manufacturing Innovation Institute and the wide potential uses for and benefits of 3D printing.

Read yesterday's story in Reuters about how the business of 3D printing is starting to make its way into individual homes and garages.

The Scientific Method in Action: Advances in Weather Forecasting

Through repeated applications of the scientific method and advances
in computer modeling, weather predication has become a 
scientific endeavor and accuracy has greatly improved.   
Image courtesy: Chris Zielecki (Flickr CC)

Meteorologists often take a lot of flack when their weather predictions aren't accurate--indeed it can be very annoying to cancel a big event for a blizzard that never materializes, or worse, very dangerous if an unexpected storm comes up while you are out hiking. Despite its foibles, though, weather forecasting has come a long way from its early roots of divining celestial signs and following limericks ("red sky at night, sailors delight; red sky in morning, sailors take warning") to become a truly scientific endeavor.

As in any scientific field, uncertainty is inherent in the data that predict the path of a hurricane or separate "clear skies" from "chance of thunderstorms."  But the accuracy of weather forecasts has greatly improved over the last century,  thanks in large part to advances in computer modeling.

Early efforts to predict the weather mathematically, by people like Vilhelm Bjerknes and Lewis Fry Richardson, highlighted the need for serious computational power to begin even approaching the level of complexity found in Earth's atmosphere.  Efforts to make weather prediction scientific, and the recognition that propagating a tiny error across a series of weather calculations could have a huge cumulative impact on the results, also spawned the field of chaos theory.  Chaos theory, which includes the popular notion of "the butterfly effect," aims to understand underlying patterns of behavior in complex systems (like weather) and to quantifying the uncertainty.

Strides in the accuracy of weather prediction are an everyday example of the scientific method in action. Modern meteorologists--as well as scientists who model long-term global climate systems--still contend with uncertainty, complexity, the limits of technology, and human errors.  But through the iterative process of the scientific method (and aided by faster, more powerful computers), they are continuously fine-tuning their models and predictions.  That's good news for science and for anyone who wants to plan a picnic or avoid a lightening strike.

LEARN MORE
Venture inside one of the modern nerve centers for weather forecasting, the National Centers for Environmental Prediction, in Nate Silver's New York Times Magazine piece "The Weatherman is Not a Moron."

Learn about some of the first computer models, which were developed for weather prediction in our module Research Methods: Modeling

Read about how weather forecasting led to the rise of chaos theory in our module Data: Uncertainty, Error, and Confidence