Scientists were plenty busy this year, with landing the 1-ton rover Curiosity on Mars, announcing the discovery of what is likely the Higgs boson and even revealing a little-dirty secret in research.

For the second year, the editors of the scientific journal Nature have announced their "Nature's 10," the top 10 scientists who mattered in 2012, with profiles that dig deeper into the personal stories behind the achievements. Here's a look at their picks.

A heavenly discovery?

A particle sought after for decades came to light in spectacular fashion on July Fourth this year, with physicists from two experiments being conducted in the Large Hadron (LHC) Collider near Geneva announcing they had found a particle that looked eerily similar to the Higgs boson, predicted to give all other matter its mass.

While several billion neurons (not to mention the Wattage used in the LHC) were behind the discovery, director general of LHC's host lab CERN, Rolf-Dieter Heuer, made sure the world heard about it, according to Nature editors. Apparently neither group was willing to claim an actual "discovery" until their evidence was proven to a certain level of certainty. With a gentle hand, Heuer nudged for the announcement, but let the scientists be scientists and stick to the facts (for instance saying they had a 5 and 4.9 sigma level of certainty, respectively), while he used, only once, the word "discovery." (A 5 sigma means there is only a one in 3.5 million chance the signal seen in the LHC data isn't real.) [Top 5 Implications of Finding the Higgs Boson]

Mars madness

Another whopper for science in 2012 was arguably the landing of the Mars rover Curiosity on the Red Planet's surface. Leading the 50-person team behind the smooth landing was engineer Adam Steltzner, of NASA's Jet Propulsion Laboratory in Pasadena, Calif. The touchdown technique was a first: Curiosity was lowered to the Martian surface on cables by a rocket-powered sky crane, one that had an alien look on its own. "Because it looked so outlandish, we all felt very exposed," Steltzner told Nature. "If it failed, people would have been like, 'You idiots.'" It didn't.

Since its spectacular touchdown, Curiosity has discovered an ancient streambed where water likely flowed for thousands of years long ago and hints of possibly life-giving organic compounds.

Hurricane Sandy Cassandra

Not all happenings were so uplifting. After Hurricane Sandy battered the East Coast and left transportation tunnels flooded and millions without power, climatologist Cynthia Rosenzweig wasn't surprised. That's because the NASA Goddard Institute for Space Studies researcher and a team of other scientists had forecasted such cataclysmic events in 2000 as part of a report for the U.S. Global Change Research Program. The dozen years of warning helped city officials incorporate climate change into city planning. Rosenzweig, who started off as a farmer in Tuscany but eventually moved from agricultural science to climate science, is now trying to assess whether those efforts reduced Sandy's damage. [On the Ground: Hurricane Sandy in Images]

Can you repeat that?

It's a dirty-little secret that many scientific results can't be reproduced. In 2006, Elizabeth Iorns, a geneticist at the University of Miami, tried to replicate a study about a cancer gene and couldn't. She found that few scientific journals wanted to publish her findings and that she got blowback from colleagues. That lit a fire in her belly to ensure that more scientific results are rigorously tested. To that end, she created a startup based in Palo Alto, Calif., called the Reproducibility Initiative. The goal of the fledgling nonprofit is to have third-party researchers replicate important scientific experiments. If the startup can make headway, it may help scientists know which results are real.

Sex bias

While it's no surprise that women are underrepresented in science, pinning that to discrimination, rather than gender differences in aptitude or interest, has been tricky. But when Yale University microbiologist Jo Handelsman showed that researchers offer fictitious female job applicants about $4,000 less in salary and rate them as less competent and worthy of mentorship than male counterparts, she produced strong evidence for sexual bias. Handelsman says she hasn't personally experienced strong bias, but became motivated to speak out about it when other women scientists described their experiences with sex discrimination.

Mad man

Timothy Gowers isn't a likelier crusader in the world of scientific journal publishing. The Cambridge University mathematician has won the Fields Medal (mathematics highest honor) and has been knighted for his influential work. But he made waves this year when he spearheaded a global boycott of the giant publishing group Elsevier, discontented with the publishing group's sky-high prices and their fight against open-access scientific publishing, which can be viewed by everyone without a subscription. The boycott has fueled growing interest in open-access publishing and may even have influenced Elsevier to withdraw its support for a controversial, anti-open access political bill. The bill, the Research Works Act, would have allowed scientists to publish research funded with U.S. taxpayer money in journals that would be closed off to the general public.

Deadly research

When Ron Fouchier, a virologist at the Erasmus Medical Center in Rotterdam, used just four genetic tweaks to create a highly lethal strain of the H5N1 bird flu that could spread through the air, it sparked a global discussion about whether such deadly pathogens should be created. Critics argued that the mutant bird flu could be accidentally released and that publishing the findings could give would-be terrorists a road-map for creating a biological weapon. Fouchier's results were eventually published in Nature with key methodological details removed, but not without a flurry of discussion over the ethics of the research. Throughout it all, Fouchier has been arguing that the research is necessary and safe. In January 2012, Fouchier and other flu researchers agreed to a moratorium on researching this particular type of flu. Now he has set his sights on a mysterious, deadly form of pneumonia that has emerged from a bat virus in Saudi Arabia.

Watching cells grow

Cedric Blanpain doesn't trust Petri dishes, sort of. This skepticism in the ability of lab-dish cell growth to replicate what happens in real life led Blanpain to uncover, in 2011, distinct stem cells in the adult mammary gland. This year, he applied a carcinogen to mouse skin and then followed tumor growth using a cell-tracking method; his results showed not all cells contribute equally to tumor growth, with some dwindling after a few cell divisions and others, the stem cells, generating thousands of clones — the tumor-generating cells. "I saw the first slide, and I said 'show me the second one.' After the fifth, I was sure what I was seeing," Blanpain told Nature.

Manslaughter verdict

A reminder that science doesn't always, and sometimes cannot, stay in the ivory towers, this year brought a devastating manslaughter verdict for six Italian scientists and one government official Bernardo De Bernardinis (an engineer by training) accused of being too reassuring about the risk of an earthquake prior to a temblor in 2009 that killed 309 individuals in the town of L'Aquila. [See Photos of L'Aquila Earthquake Destruction]

Seismologists across the globe expressed appall at a verdict that didn't account for the fact that earthquakes cannot be predicted with any level of accuracy. Even so, De Bernardinis not only showed compassion for those who lost loved ones in the earthquake, but he also showed up at every hearing, Nature reported. Insisting that he only listened to what the seismologists told him before the infamous press conference at the center of this trial, De Bernardinis also admits he should've waited for a concise statement from the scientists before addressing the public. Now, he hopes the trial will lead to better risk-prevention systems in Italy that have clear-cut expectations for scientists, government officials and the media.

Sequencing genomes

The head of the Chinese genome-sequencing institute, BGI, Jun Wang has shown modesty and confidence in the significance of what he and colleagues are doing. And the numbers speak worlds: BGI is leading the sequencing of 10,000 vertebrates (animals with backbones), 5,000 insects and other arthropods, and more than 1,000 birds, including some extinct ones. In this year alone, BGI was listed in 100 scientific publications, Nature reports, adding the organization is a "main player" in the 1,000 Genomes Project Consortium, whose aim is to find genetic factors behind disease.

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