The , a daily record of atmospheric carbon dioxide, has been running continuously since March 1958, when a carbon dioxide monitor was installed at Mauna Loa in Hawaii. On the first day, the observatory measured a carbon dioxide concentration of 313 parts per million (ppm). The number means there were 313 molecules of carbon dioxide in the air per every million air molecules.

Now, the Keeling Curve has reached 400 ppm for the first time in human history, with a new measure of 400.03 ppm. The data are preliminary, pending quality control checks, according to the National Oceaninc and Atmospheric Administration (NOAA). []

The rollover from 399 won't make an appreciable difference in climate by itself, but the continuing rise in greenhouse gas concentration is already doing so, climate scientists say.

A concentration of 400 ppm is "a new high-water mark, of course, and more than anything else, has symbolic significance," said Michael Mann, a climate researcher at Pennsylvania State University.

Upward creep

Each year, the Keeling Curve shows an increase in carbon dioxide in the atmosphere which peaks in May. The number then drops, reaching a minimum in October. This maximum-minimum pattern, repeated seasonally, reveals how trees withdraw carbon dioxide from the air in summer to grow and then release it through dead, decaying leaves and wood in the winter.

But humans release carbon dioxide into the air, too, by . This activity has caused the Keeling Curve to creep ever upward since 1958: The lows get a little higher each year, as do the highs.

"It is a reminder of just how uncontrolled this dangerous experiment we're playing with the planet really is," Mann told LiveScience.

What 400 ppm means

In the 1,000 years before the Industrial Revolution of the 18th century, atmospheric carbon dioxide held steady at around 270 to 280 parts per million.

Scientists believe that the most recent period with a 400 ppm level of carbon dioxide in the atmosphere was the Pliocene, between five million and three million years ago, according to the Scripps Institution of Oceanography, which keeps track of the Keeling Curve.

It was a different world. Global average temperatures were between 5.4 and 7.2 degrees Fahrenheit (3 to 4 degrees Celsius) higher than today, and sea level was as much as 131 feet (40 meters) higher in some places. Even the least-affected regions saw16 feet (5 meters) higher than today's.

A major difference, though, is the speed at which carbon dioxide is rising today. Typically, the Keeling Curve shows increases of 2 to 2.5 ppm a year, Mann said. In the 1950s and 1960s, carbon dioxide increased by less than 1 ppm each year, according to Scripps Institution of Oceanography.

"We're on course for more than 450 ppm in a matter of decades if we don't get ourunder control quite soon," Mann said.

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Financial details of the acquisition by the British drugmaker's MedImmune unit were not disclosed.

AstraZeneca's new CEO Pascal Soriot said last month he planned to build up the company's sparse drug pipeline by striking more deals, with cardiovascular and metabolic disease a particular priority.

Cardiovascular and metabolic disease is one of three core therapy areas for AstraZeneca - along with oncology and respiratory/inflammation - but the company currently has few experimental compounds for such conditions.

AlphaCore will help plug the gap, although it will not deliver any marketable products for many years. Its leading drug candidate ACP-501, a genetically engineered liver-derived enzyme called LCAT, only completed Phase I clinical tests last year.

Drugs need to go through three phases of lengthy tests before being approved for sale.

The hope is that ACP-501 will help in the management of cholesterol to reduce the risk of heart attacks and strokes. It could also play a role in a rare, hereditary disorder called familial LCAT deficiency in which the LCAT enzyme is absent.

"As the science in this area continues to evolve, we are committed to exploring unique pathways that could lead to new combination or standalone therapies for patients living with chronic and acute cardiovascular diseases," said MedImmune head Bahija Jallal.

(Reporting by Ben Hirschler; Editing by Tom Pfeiffer)

Singh was initially found by the PGA Tour to have breached the sport's doping rules after using a spray, which contains a banned substance, to treat an injury but was later cleared of any wrongdoing after winning an appeal.

He filed a lawsuit in the Supreme Court of the State of New York on Wednesday, and issued a statement saying the PGA Tour had damaged his reputation.

"I am proud of my achievement, my work ethic and the way I live my life," Singh said in the statement.

"The PGA Tour not only treated me unfairly, but displayed a lack of professionalism that should concern every professional golfer and fan of the game."

Although he never failed a drugs test, Singh was deemed to have breached golf's rules on doping when he told Sports Illustrated earlier this year he had used deer antler spray.

The spray was found to have contained small extracts of IGF-1, a growth hormone on the World Anti-Doping Agency's (WADA) list of prohibited substances.

The PGA Tour imposed a sanction on Singh following his admission but the Fijian appealed, saying he was unaware the spray contained any banned substances.

He was cleared last week when WADA informed the PGA Tour the use of deer antler spray was not prohibited unless a positive test resulted.

Singh's lawyers said on Wednesday the PGA Tour violated its duty of care by suspending the golfer without properly investigating the case.

"The PGA Tour could have known by conducting some basic testing and research, the product that Singh sprayed contained no active biological ingredient and could not possibly have provided any performance enhancement," Singh's attorney, Peter R. Ginsberg, said in a statement.

"The PGA Tour has now finally admitted that the use of deer antler spray is not prohibited.

"Rather than performing its duties to golfers first, and then determining whether there had been any violation of the Anti-Doping Program, the PGA Tour rushed to judgment and accused one of the world's hardest working and most dedicated golfers of violating the rules of the game."

The PGA did not immediately comment on the lawsuit.

Singh, 50, was ranked number one in the world on three separate occasions between 2004 and 2005. He also won three majors: the 2000 Masters and the 1998 and 2004 PGA Championship. (Reporting by Julian Linden in New York; Editing by Frank Pingue)

(Reuters) - A fierce wildfire threatening 4,000 homes northwest of Los Angeles was about 30 percent contained on Saturday as higher humidity and cooler temperatures helped firefighters, fire department spokesmen said.

The fire in coastal Ventura County has blackened about 28,000 acres of rugged brush land since it started on Thursday. It was not expected to be under control until May 13, Ventura County Fire Department spokesman Tom Kruschke said.

A drop from record-high temperatures on Friday and lighter, cooler winds off the Pacific Ocean helped the 1,900 firefighters brought in from across California.

"We're getting much more favorable weather conditions here. We don't have the high winds and the high temperatures," Kruschke said.

Light rain forecast for Sunday and heavier rain expected for Monday and Tuesday also could help firefighters and aircraft battling what authorities are calling the Springs Fire.

About 4,000 homes have been threatened by the fire and 15 damaged. No injuries have been reported from the fire, but a firefighter and a civilian were hurt in a vehicle collision, the department said on its website.

A spokesman for the Ventura County Sheriff's Department said an evacuation order affecting several thousand people had been lifted for all but a small area.

Less than 12,000 acres had burned since the mid-April start of the Southern California fire season, until the sharp increase this week with the Springs Fire and five smaller blazes around the state, said Daniel Berlant, a spokesman for the state's Department of Forestry and Fire Protection.

The department had moved ahead its official start date for the season by two weeks because of dry conditions, already at levels typical for June or July, Berlant said. Snow pack in California's Sierra Nevada mountains is 17 percent of normal.

Some weather forecasters have predicted the season will get worse with a summer of high temperatures and drought throughout much of the U.S. West.

The fire forced the closure of California State University Channel Islands in Camarillo, where the temperature was a record 96 degrees Fahrenheit (36 Celsius) on Friday. It is tentatively scheduled to reopen on Sunday, the school said on its website.

The Point Mugu U.S. Naval Air Station has lifted its order that non-essential personnel stay home because of the fire. A base housing unit was evacuated on Friday because of heavy smoke.

(Reporting by Ian Simpson in Washington; Editing by Doina Chiacu and Vicki Allen)

(Reuters) - Allergan Inc said approval of its Darpin eye drug could be delayed up to two years, providing a new boost to Regeneron Pharmaceuticals Inc whose successful treatment, Eylea, stands to gain from a lack of new competition.

Shares of Allergan, which makes wrinkle treatment Botox, fell 13.1 percent after the company said mid-stage trial results of Darpin did not warrant an immediate move into far larger late-stage trials. Regeneron shares closed up 10.3 percent.

If eventually approved, Darpin would also compete with Roche Holding AG's, Lucentis, to treat age-related macular degeneration - the most common form of blindness in the elderly.

Adnan Butt, an analyst with RBC Capital Markets, said Darpin's delay was "great news" for Regeneron. He noted that Wall Street had feared the Allergan drug might have a superior clinical profile to Eylea.

"This gives Eylea even more time to become entrenched as the drug to beat," Butt said.

He estimates that each year of Darpin delay will translate into an upside of about $15 to $20 for Regeneron shares, now trading at about $240.

Eylea, which was approved in November 2011, had sales last year of $838 million. Regeneron expects 2013 Eylea sales of $1.2 billion to $1.3 billion. Company officials would not comment on the setback for Allergan's drug.

Regeneron is expected to report first quarter results on Friday and could update its sales projections.

Allergan Chief Executive David Pyott said on a conference call that a mid-stage trial of Darpin showed some product differentiation over Lucentis, but did not support directly moving to late-stage development.

The company now plans to perform additional mid-stage trials to assess Darpin, which will delay its potential approval by one to two years.

"There was a rush to ascribe a lot of value to Darpin and our view is that this is still very much an unproven asset with limited data," Piper Jaffray analyst David Amsellem said.

"The earliest it could get to market now is likely 2019," Amsellem said. "If you couple that with the setback of the hair loss product, the late-stage pipeline for Allergan right now is really quite thin."

A mid-stage trial of Allergan's hair loss treatment Bimatoprost Scalp also failed to provide sufficient efficacy to proceed to a late-stage study, further weighing on company shares.

ROOM TO GROW

Regeneron in the past two years has vaulted seemingly out of nowhere to become one of the world's biggest biotechnology companies, thanks largely to Eylea.

The company has repeatedly raised its sales forecasts for the drug, which is injected into the eye, as it steadily steals market share from Lucentis.

Some specialty pharmacies also use Roche's Avastin cancer drug, which works the same way as Lucentis, but is far less expensive, when divided into smaller portions for treating macular degeneration.

Roche has said that dividing Avastin through a procedure not closely monitored by health regulators, called compounding, could compromise its sterility.

Regeneron Chief Executive Leonard Schleifer said in a recent interview that sales of Eylea could jump sharply if potential rivals stumble, or if U.S. regulators clamp down on the compounding of Avastin for eye use.

Moreover, he said some analysts believe Eylea sales could swell if it is approved for a new indication called diabetic macular edema now in late-stage trials. Lucentis is already approved for the condition.

"So Eylea is a growth story unto itself, with lots of room to still grow," Schleifer said.

Allergan on Wednesday also posted a higher-than-expected quarterly profit, helped by strong sales of Botox.

Net income for the first quarter fell to $12.5 million, or 4 cents per share, due to a loss of $259 million from discontinued operations. Profit was $229.8 million, or 74 cents per share, a year earlier.

Excluding special items, Allergan earned 98 cents per share. Analysts were expecting 96 cents, according to Thomson Reuters I/B/E/S.

Global company sales rose 8 percent to $1.46 billion, above Wall Street's average estimate of $1.44 billion.

Sales of Botox, which is also approved for treating migraine headaches, overactive bladder and underarm sweating, rose 15 percent to $457.9 million.

Allergan said it now expects 2013 adjusted earnings of $4.70 to $4.76 per share, compared with its prior outlook of $4.75 to $4.83 a share.

The company forecast a second-quarter profit of $1.18 to $1.20 per share, below analysts' average estimate of $1.22 a share. The new forecasts reflect the impact of its MAP Pharmaceuticals acquisition earlier this year.

Allergan shares fell $14.88 to $98.67 on the New York Stock Exchange, while Regeneron shares rose $25.15 to $237.29.

(Reporting by Esha Dey in Bangalore and Bill Berkrot in New York; Editing by Michele Gershberg, Sreejiraj Eluvangal, Carol Bishopric and Andre Grenon)

A corrected version of the story is below:

Coursera to offer new MOOC options for teachers

Coursera to offer new set of online course options targeting teacher education

By JUSTIN POPE

AP Education Writer

A leading platform for the popular "massive open online courses" offered by elite universities is moving into a new realm: the expansive field of continuing education for teachers.

Coursera, the California-based for-profit platform for MOOCs from 62 leading universities such as Stanford, Princeton and the University of Pennsylvania, planned to announce Wednesday a new range of partners that include education schools and, in a first, non-degree granting institutions that help train teachers.

The announcement would give teachers pursuing their continuing education requirements, or courses that could give them a salary boost, a new set of options to learn from master professors at leading education schools such as Vanderbilt and the University of Virginia, along with a handful of museums and other institutions.

It would be up to the schools or districts that employ teachers to decide whether the courses meet their requirements, but Coursera co-founder Daphne Koller said she expects they will find them high-quality. Another advantage: The courses are free a preferable option to the training, often expensive, that districts often pay for themselves.

The classes could also be more flexible for busy teachers, Koller said, and their large size could be an advantage.

"If you're the sole physics teacher in a small town somewhere, you really don't have a peer network," Koller said in a telephone interview. "This is creating a nationwide and in fact a worldwide peer network."

Coursera currently offers 341 free courses built around video lectures and interactive components, on topics ranging from pre-calculus to introduction to guitar, but has been moving more into more professionalized continuing education topics. Nearly 3.5 million students have signed up, though most don't finish the courses.

Coursera isn't a university so it cannot award credit itself, though for a small fee students can get their completion verified, and Coursera and other MOOC providers are increasingly partnering with institutions on "blended learning" models with institutions that are able to award credit.

The new offerings will include courses with titles such as "Art and Inquiry: Museum Teaching Strategies For Your Classroom" and "Surviving Your Rookie Year of Teaching." Dave Levin, co-founder of the KIPP schools network, will offer a course on "Teaching Character and Creating Positive Classrooms."

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Online: www.coursera.org

Follow Justin Pope on Twitter at http://www.twitter.com/JustinPopeAP

The 84-page white paper goes on to describe how Chinas growing interest in cyber could allow it to disable or disrupt the United States in the event of a shooting war. Weve seen some of this rhetoric filter into the national debate over cybersecurity. Gaining access to U.S. power grids, public health systems, and transportation networks is the first step to taking those assets offline.

But that doesnt really explain some of the other hacking attempts that have been attributed to the Chinese government. What possible military value could there be to hacking The Washington Post, for instance? Where does that fit in, strategically?

To answer that question, maybe we need to reverse our perspective.

Unlike the Chinese, said Adam Segal, a cybersecurity scholar at the Council on Foreign Relations, we dont have a comprehensive view of national power. So, the DoD isnt going to spend too much time talking about the links between (economic espionage) and future military power.

But maybe we should. After all, if China sees a connection there, whats to say its next actions wont be informed by it? Just because the American mind interprets a divide between public and private institutions doesnt mean that its opponents will respect that distinction.

The media world provides the perfect case. While most of us regard the press as independent from -- or even opposed to -- government, news organizations in China arent an example of power distributed. Just the opposite. And if youre a Chinese hacker whose experience is that theres no daylight between media and bureaucracy, then itd make total sense to think that penetrating one will get you inside the other. That may not be how journalism actually works in the United States, but thats not the point. The point is that establishing whether Beijing thinks this way is a prerequisite to disrupting its activities.

Im not the first to raise this issue. As The Washington Posts Ezra Klein wrote back in February, what the Chinese are looking for is:

Thing is, there is no such document -- only a collection of ordinary humans squabbling for territory and resources. Americans take one look at Congress and grasp that intuitively; but foreign observers might not. And thats valuable intelligence right there.

Its one thing to know your opponent. Its another to understand the way in which you know your opponent. And its something else entirely if your opponent is wise to it, too.

Stanton underwent an MRI exam Tuesday and said the diagnosis was a grade-two strain on the one-to-three scale for the injury. He was hurt trying to beat out a grounder in Monday's 15-inning victory over the New York Mets, and was placed on the 15-day disabled list.

The injury occurred just as last year's NL slugging leader showed signs of emerging from a prolonged slump to start the season. He hit his first home run Saturday and two more Sunday.

"Awesome timing," Stanton said facetiously. "It's a tough break. Pretty frustrating. It's just one of those freak things. There's never a good time, but this was probably one of the worst times to do it."

Last year Stanton hit 37 home runs despite missing 39 games because of injuries. Now the Marlins, already saddled with the worst record in the majors, will be without their best hitter for several weeks.

"If we could just erase all of April, that would be lovely," Stanton said.

He'll be replaced in right field by 22-year-old Marcell Ozuna, who was recalled from Double-A Jacksonville to make his major-league debut.

"When I received the call, I felt very excited," Ozuna said. "I didn't sleep last night."

With Stanton due to become eligible for arbitration after the season, there's already speculation the thrifty Marlins will trade him, and Ozuna would be the leading replacement candidate.

The Dominican was hitting .333 with five homers and 15 RBIs in 10 games with Jacksonville. He's a career .274 hitter in the minors who hit at least 22 home runs each of the past three seasons.

NEW YORK (Reuters) - Stocks dipped in thin volume on Friday, though the market had a strong week overall despite a mixed bag of earnings and weak economic figures.

Shares of online retailer Amazon.com Incposted the largest daily drop in 15 months after the company reported results late on Thursday. It was Friday's biggest drag on the S&P 500 and Nasdaq indexes.

Gains in shares of Chevron Corpbuoyed the blue-chip Dow industrials.

The market fell early after a negative surprise from the gross domestic product report, but the decline attracted bargain-hunting investors late in the session. Major indexes posted solid gains for the week.

J.C. Penney Cowas the S&P 500's biggest percentage gainer, up 11.5 percent to $17 after CNBC reported Goldman Sachs lined up a $1.75 billion loan for the retailer. The news added to previous gains a day after investor George Soros reported a 7.9 percent passive stake in the company.

"We traded off a decent amount after the GDP number but we didn't break any technical levels or really didn't get much momentum in the selloff past late morning," said Paul Zemsky, head of asset allocation at ING Investment Management in New York.

"I guess there was some bottom fishing. There was so much fear of poor earnings going into earnings season that this is still somewhat of a positive surprise."

The Dow Jones industrial averagerose 11.75 points or 0.08 percent, to 14,712.55, the S&P 500lost 2.92 points or 0.18 percent, to 1,582.24 and the Nasdaq Compositedropped 10.72 points or 0.33 percent, to 3,279.26.

For the week, the Dow gained 1.1 percent, the S&P added 1.7 percent and the Nasdaq rose 2.3 percent.

Of the 271 companies in the S&P 500 that have reported earnings to date for the first quarter, 69 percent have beaten analyst expectations - above the 63 percent average since 1994 and slightly over the 67 percent beat rate over the past four quarters.

Eastman Chemicaldropped 5.1 percent to $68.97 a day after posting results, to lead percentage declines among S&P materials , which was the worst performing sector of the index with a 1.4 percent drop.

The S&P traded Thursday within a point of its historic closing high set earlier this month and the 1,593 level is expected to be technical resistance in the near future.

Gross domestic product expanded at a 2.5 percent rate in the first quarter, below estimates of 3 percent, heightening fears the U.S. economy could struggle to cope with deep government spending cuts and higher taxes that kicked in earlier this year.

Amazon.com shed 7.2 percent to $254.81 after it said revenue growth slowed in the first quarter as the company struggled overseas, but margins jumped on lower shipping expenses.

Chevron rose 1.3 percent to $120.04 after it posted earnings that beat expectations, even as lower oil prices bit into the profits of the second largest U.S. oil company.

The PHLX housing sector indexgained 1 percent, getting a lift from D.R. Horton Incafter the No. 1 U.S. homebuilder reported earnings. D.R. Horton shares closed at their highest in six years after an 8.7 percent jump to $26.60.

About 5.7 billion shares changed hands on the New York Stock Exchange, the Nasdaq and NYSE MKT, below the daily average so far this year of about 6.4 billion shares.

On the NYSE, roughly seven issues fell for every five that rose and on Nasdaq about three fell for every two advancing issues.

(Reporting by Rodrigo Campos; Editing by Kenneth Barry)

Orellana's publicist said in a statement late Thursday that he is "currently alive and well" after being shot Wednesday night, noting he was in the wrong place at the wrong time while hanging out with friends. Police are investigating.

The statement said he was in his neighborhood when he was shot, but didn't specify a city. Orellana's hometown is Providence, R.I.

The producer's manager, George Moore, a record label executive and producer known as DukeDaGod posted on Twitter a picture of Orellana in a hospital bed Thursday with the words: "Everyone wish my brother (at)araabmuzik a healthy & pleasant recovery!!!!"

The statement said Orellana appreciates fan support and "Araab is looking forward to a speedy recovery and returning to the stage as soon as he can."

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Online:

http://araabmuzikmvp.com