What are the limits of automated Twitter sentiment classification? We analyze a large set of manually labeled tweets in different languages, use them as training data, and construct automated classification models. It turns out that the quality of classification models depends much more on the quality and size of training data than on the type of the model trained. Experimental results indicate that there is no statistically significant difference between the performance of the top classification models. We quantify the quality of training data by applying various annotator agreement measures, and identify the weakest points of different datasets. We show that the model performance approaches the inter-annotator agreement when the size of the training set is sufficiently large. However, it is crucial to regularly monitor the self- and inter-annotator agreements since this improves the training datasets and consequently the model performance. Finally, we show that there is strong evidence that humans perceive the sentiment classes (negative, neutral, and positive) as ordered.

TIME TO RE-FILE: "A U.S. judge on Monday partly dismissed a lawsuit filed by Twitter in which the social media company argued it should be allowed to publicly disclose more details about requests for information it receives from the U.S. government," Reuters reports. "U.S. District Judge Yvonne Gonzalez Rogers in Oakland, California also gave Twitter the opportunity to re-file its lawsuit to include more details about government decision-making, in order to try to move its claims forward." NEXT IN SMART GUNS: "The departments of Defense, Homeland Security and Justice released a report on April 29 outlining a strategy for promoting smart gun technology to reduce gun violence," FCW reports. "There are two basic types of smart gun technologies. One keeps a gun from being fired by anyone other than the weapon's authorized user. The other embeds a small chip into guns to make it easier to track stolen weapons. The government's goal is to encourage gun manufacturers to find new ways to integrate the technology into their devices while ensuring the firearms maintain their dependability."

Nasa has announced that it has found evidence of flowing water on Mars. Scientists have long speculated that Recurring Slope Lineae -- or dark patches -- on Mars were made up of briny water but the new findings prove that those patches are caused by liquid water, which it has established by finding hydrated salts. Several hundred camped outside the London store in Covent Garden. The 6s will have new features like a vastly improved camera and a pressure-sensitive "3D Touch" display

Nasa has announced that it has found evidence of flowing water on Mars. Scientists have long speculated that Recurring Slope Lineae -- or dark patches -- on Mars were made up of briny water but the new findings prove that those patches are caused by liquid water, which it has established by finding hydrated salts. Several hundred camped outside the London store in Covent Garden. The 6s will have new features like a vastly improved camera and a pressure-sensitive "3D Touch" display

Up to 1.6 million patients have had their private medical files passed on to Google without their permission, it was revealed today The internet giant was given the data by one of the largest NHS trusts to develop an app to monitor possible kidney failure. The encrypted information includes the names and medical histories of every patient who had stayed in hospital overnight or attended A&E in the past five years. None of the patients was told beforehand and the revelation has exposed the ease with which private companies can obtain highly sensitive medical information without consent. Privacy campaigners told MailOnline that the revelations exposed the public's lack of power and control over their own personal details. Experts say the deal between Google and the Royal Free NHS Trust could set a precedent for patient data to be routinely passed on to private firms.

In 1985, for example, Sandberg-Diment declared laptops would never be a mass-market technology. "On the whole, people don't want to lug a computer with them to the beach or on a train to while away hours they would rather spend reading the sports or business section of the newspaper," he wrote. "Somehow, the microcomputer industry has assumed that everyone would love to have a keyboard grafted on as an extension of their fingers. It just is not so ... Because no matter how inexpensive the machines become, and no matter how sophisticated their software, I still can't imagine the average user taking one along when going fishing." Before that, he had predicted people would never use laptops on airplanes because the Federal Aviation Administration would ban the devices.

Think of the gear you can't live without: The smartphone you constantly check. The camera that goes with you on every vacation. The TV that serves as a portal to binge-watching and -gaming. Each owes its influence to one model that changed the course of technology for good. Some of these, like Sony's Walkman, were the first of their kind. Others, such as the iPod, propelled an existing idea into the mainstream. Some were unsuccessful commercially, but influential nonetheless. And a few represent exciting but unproven new concepts (looking at you Oculus Rift). Rather than rank technologies--writing, electricity, and so on--we chose to rank gadgets, the devices by with consumers let the future creep into their present. The list--which is ordered by influence--was assembled and deliberated on at (extreme) length by TIME's technology and business editors, writers and reporters.

There is a lot of excitement about artificial intelligence (AI) and how to create computers capable of intelligent behavior. After years of steady but slow progress on making computers "smarter" at everyday tasks, a series of breakthroughs in the research community and industry have recently spurred momentum and investment in the development of this field. Today's AI is confined to narrow, specific tasks, and isn't anything like the general, adaptable intelligence that humans exhibit. Despite this, AI's influence on the world is growing. The rate of progress we have seen will have broad implications for fields ranging from healthcare to image- and voice-recognition.

The next NASA Mars rover boasts an important mission – finding traces of previous life – but it has a budget about 1 billion less than its predecessor, Curiosity. Despite the limited cash flow, NASA intends to improve various aspects of the new rover, including its robotic arms and landing mechanisms. Sierra Nevada Corporation's (SNC) Space Systems announced Monday it had been awarded a contract to build these new parts for the budget rover, marking the 13th time SNC has supplied equipment and parts for a mission that will reach the red planet. "Sierra Nevada has been a terrific partner on our planetary robotic missions for a long time now," said Matt Wallace, Mars 2020 deputy project manager, in a phone interview with The Christian Science Monitor. "They were the obvious first choice."

It's no secret that quantum computers could render many of today's encryption methods useless, and now the U.S. National Institute of Standards and Technology wants the public to help it head off that threat. The federal agency recently published a report focusing on cryptography in a quantum world that outlines a long-term approach for avoiding the problem before it happens. "There has been a lot of research into quantum computers in recent years, and everyone from major computer companies to the government want their cryptographic algorithms to be what we call'quantum resistant,'" said NIST mathematician Dustin Moody. "So if and when someone does build a large-scale quantum computer, we want to have algorithms in place that it can't crack." Encryption often relies on the challenge of factoring large numbers to ensure security, but researchers at MIT and the University of Innsbruck in Austria recently demonstrated what they said is the first five-atom quantum computer capable of cracking such encryption schemes.