Nell Greenfieldboyce

Nell Greenfieldboyce is a NPR science correspondent.

With reporting focused on general science, NASA, and the intersection between technology and society, Greenfieldboyce has been on the science desk's technology beat since she joined NPR in 2005.

In that time Greenfieldboyce has reported on topics including the narwhals in Greenland, the ending of the space shuttle program, and the reasons why independent truckers don't want electronic tracking in their cabs.

Much of Greenfieldboyce's reporting reflects an interest in discovering how applied science and technology connects with people and culture. She has worked on stories spanning issues such as pet cloning, gene therapy, ballistics, and federal regulation of new technology.

Prior to NPR, Greenfieldboyce spent a decade working in print, mostly magazines including U.S. News & World Report and New Scientist.

A graduate of Johns Hopkins, earning her Bachelor's of Arts degree in social sciences and a Master's of Arts degree in science writing, Greenfieldboyce taught science writing for four years at the university. She was honored for her talents with the Evert Clark/Seth Payne Award for Young Science Journalists.

Scientists have found a microbe that does something textbooks say is impossible: It's a complex cell that survives without mitochondria.

Mitochondria are the powerhouses inside eukaryotic cells, the type of complicated cell that makes up people, other critters and plants and fungi. All eukaryotic cells contain a nucleus and little organelles — and one of the most famous was the mitochondrion.

NASA announced Tuesday the discovery of an unprecedented number of planets beyond our solar system — astronomers have confirmed the existence of 1,284 new worlds orbiting distant stars.

These planets beyond our solar system — exoplanets — were discovered with the help of NASA's Kepler Space Telescope, which launched in 2009.

A trio of newly discovered Earth-sized planets looks ideally suited to search for signs that these alien worlds might be able to support life.

The planets orbit close to an unusually small, reddish star that's about one-eighth the size of our sun and is far cooler, researchers report in the journal Nature.

Scientists say they have made an atlas of where words' meanings are located in the brain. The map shows that words are represented in different regions throughout the brain's outer layer.

The largest research hospital in the world, the National Institutes of Health Clinical Center in Bethesda, Md., needs reform so that patient safety is always the priority — and never subservient to the demands of science.

The National Institutes of Health has suspended work in two facilities that manufacture products given to people who are enrolled in research studies, saying the facilities haven't complied with safety standards designed to protect already-sick people from inappropriate risks.

Finding a new planet that orbits a distant star isn't such a big deal anymore — astronomers have discovered around 2,000. But no one knows if any of these planets has a moon.

That might change this year, if a moon-hunting project goes as planned.

Scientists have discovered a supermassive black hole that may be the biggest ever spotted — and its location in a ho-hum group of galaxies suggests that cosmic monsters like this one might be more common than astronomers previously thought.

The Department of Labor is issuing a long-awaited and controversial rule Thursday aimed at better protecting workers from inhaling silica dust.

The new rule dramatically reduces the allowed exposure limits for workers in a slew of industries, from construction to manufacturing to fracking.

As scientists struggle to understand the threat posed by Zika virus, there's another viral infection that's a known danger in pregnancy and that harms 100,000 babies a year, even though it has been preventable with a vaccine since 1969.

The disease is rubella, or German measles. Like Zika, the rubella virus often causes either a mild rash or no symptoms at all.

Anyone can follow the pregnancy of a monkey infected with Zika virus in real time, thanks to an experiment in data sharing that's unusual for biology.

One of the best ways to understand Zika virus might be to deliberately inject it into volunteers.

That idea may sound a little crazy, but it's not unprecedented. And some researchers are hoping the approach could help speed up the search for an effective Zika vaccine.

Right now, a bunch of labs are pursuing different ways of making a vaccine against Zika, mostly because of the concern that the virus might be linked to the birth defect called microcephaly.

Tiny eggs have started hatching this week at the San Diego Zoo, and scientists there are celebrating the arrival of baby tree lobsters.

It's all part of a conservation effort for the Lord Howe Island stick insect. The huge, black, shiny creature, also known as a tree lobster, is a superstar of the entomological world, because its history is such a strange saga of passion and commitment.

When Carolyn Coyne's lab at the University of Pittsburgh recently tried to order a sample of Zika virus from a major laboratory supplier, they were told it was out of stock.

"They are actually back-ordered until July for the virus," Coyne says. "At least that's what we were told." She ended up obtaining Zika from another source, and it arrived at her lab Tuesday.

Mice were much healthier and lived about 25 percent longer when scientists killed off a certain kind of cell that accumulates in the body with age.

What's more, the mice didn't seem to suffer any ill effects from losing their so-called senescent cells.

Ancient Babylonian astronomers tracked the motion of Jupiter using a technique that historians had thought was invented some 1,400 years later, in Europe.

Some octopuses intimidate their neighbors by turning black, standing tall and looming over them threateningly, like an eight-armed Dracula.

That's according to a study published Thursday that helps show that octopuses aren't loners, contrary to what scientists long thought; some of the invertebrates have an exciting social life.

The state of New Jersey has been trying to help jurors better assess the reliability of eyewitness testimony, but a recent study suggests that the effort may be having unintended consequences.

That's because a new set of instructions read to jurors by a judge seems to make them skeptical of all eyewitness testimony — even testimony that should be considered reasonably reliable.

The astronomer whose work helped kick Pluto out of the pantheon of planets says he has good reason to believe there's an undiscovered planet bigger than Earth lurking in the distant reaches of our solar system.

A mind-boggling stellar explosion is baffling astronomers, who say this cosmic beast is so immensely powerful that no one's sure exactly what made it go boom.

The recently discovered inferno is about 200 times more powerful than a typical exploding star, or supernova, and 570 billion times brighter than our sun. It was first spotted in June by the All-Sky Automated Survey for Supernovae, nicknamed the "Assassin" project, so it's called ASASSN-15lh.

Former United Nations bioweapons inspector Rocco Casagrande has a Ph.D. in experimental biology from MIT. He's got a rational, science-loving mind, so he's not the kind of guy you'd expect to have a big picture of a tarot card over his office desk.

"I like what it symbolizes," says Casagrande, hastening to explain he doesn't believe in tarot. He just thinks that this particular card, known as the Hanged Man, illustrates something important for solving problems.

The United Nations climate summit is over, the weary diplomats have gone home, and now the historic deal is being dissected by scientists.

About 600 scientists and engineers, including former employees of the National Oceanic and Atmospheric Administration (NOAA), have signed on to letters urging the head of that agency, Kathryn Sullivan, to push back against political interference in science.

As diplomats argue in Paris over a new global agreement to fight climate change, their work is driven by scientists' dire predictions of how unchecked warming will transform our planet decades and centuries from now.

But how can researchers be so sure of what will happen that far off?

Leaders from around the world are converging on Paris for the 2015 U.N. Climate Change Conference. The two-week event is designed to allow countries the chance to come to an agreement on stifling climate change.

Below are 10 questions and answers that should better prepare you for the conference and what to expect during and after its completion.

Click the audio link at the top of this page to listen to "Heating Up," NPR's special on climate change, hosted by Ari Shapiro. Share it, download it, take it with you.

Cod was once so plentiful in New England that legend had it you could walk across the local waters by stepping on the backs of the fish.

Now, though, this tasty species is in such trouble there that cod fishing is practically shut down.

And scientists say it looks like rapid warming in the Gulf of Maine explains why regulators' recent efforts to help the cod while allowing fishing were a failure.

When you go out with friends to a bar or a restaurant, there's always this awkward moment when the waiter shows up with the check and you've got to figure out how to split the bill. Well, something similar is happening right now in climate change negotiations.

The United Nations is trying to get nearly 200 countries to agree on a plan for how to fight global warming. This week negotiators are in Bonn, Germany, for their last meeting before the final summit starts Nov. 30 in Paris.

Scientists have just made a breakthrough in understanding how clouds interact with the surrounding air by studying some of the most boring clouds you can imagine in unprecedented detail.

"If you ask a child to draw a cloud they would draw a white puffy cloud floating in the air all by itself — and that's the kind of cloud we were looking at," says Raymond Shaw, an atmospheric scientist at Michigan Technological University.

Everyone knows that caffeine can keep you awake, but a new study shows that the world's most popular drug can actually interfere with your body's internal sense of time.

"The circadian clock is way beyond 'sleep and wake,' " says Kenneth Wright, a sleep and circadian physiologist at the University of Colorado, Boulder. "The circadian clock is present in cells throughout our entire body. It's in your fat cells; it's in your muscle cells. It's in your liver, for example, as well as in your brain."

Scientists today laid out a truly worst-case scenario for global warming — what would happen if we burned the Earth's entire supply of fossil fuels.

Virtually all of Antarctica's ice would melt, leading to a 160- to 200-foot sea level rise.

"If we burn it all, we're going to melt it all," says Ken Caldeira, a climate scientist at the Carnegie Institution for Science.

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