Except that this year, there aren't any, exactly. Instead of marking down prices on Macs or iPads, Apple is giving out Apple Store gift cards to purchasers of various products. The cards are worth an estimated 10-15% of the price for certain Apple devices, and more for accessories.

Online and in its North American retail stores, Apple was offering gift cards of up to $150 for the purchase of a Mac, up to $75 for an iPad and up to $50 for an iPod. No gift cards were being offered for iPhones or the new iPad Mini, which went on sale earlier this month.

In its European stores, Apple was offering modest discounts on products instead of gift cards. Online sales in the United States began after midnight Pacific time on Friday. Many brick-and-mortar Apple Stores opened at 6 a.m.

Some of Apple's competitors are sticking with more traditional Black Friday discounts. A number of items at the Microsoft Store are on sale, and the Sony Store also has a number of Black Friday deals.

Fans camped overnight for a chance to get their hands on one of the consoles.

The first-come first-served launch was considered one of the only ways for people to get hold of a console before Christmas.

Amazon said customers who had not pre-ordered before 13 November would not receive a console in time for Christmas.

The PlayStation 4 was released in the UK a week after Microsoft's Xbox One which sold a million units in the first 24 hours worldwide.

The launches are seen as a fight for dominance in the key Christmas season says the BBC's technology correspondent Rory Cellan-Jones.

Imran Choudhary was the first in the queue outside the venue in Covent Garden, London.

"It was always my goal to try and be one of the first people in the country to get hold of a PS4," he said.

Online scams The chief executive of Sony's computer entertainment division, Andrew House, said: "We are trying to create a much more social and connected feeling. The whole goal of PlayStation 4 is to connect people via play, in a way that they maybe have not had before."

Customers who had placed online pre-orders with Amazon before 6 August were given the option of receiving their console on release day.

Anyone ordering after 14 November will have to wait until after Christmas for delivery, the company said.

The console was sold out on Game's website and only people who had paid a deposit when pre-ordering were guaranteed to receive a console before Christmas. Customers have been warned to be careful of online scams involving consoles. NetNames, a company which advises brands on protecting their online reputation, said it had seen an increase in marketplace websites offering cheap consoles, sometimes in countries where they have not yet been launched.

"To avoid falling victim to the latest online scams, consumers need to remember that if the price seems too good to be true, it probably is," said NetNames product director of brand protection, Haydn Simpson.

Both the Xbox One and the PlayStation 4 have suffered problems after their launches in the US and worldwide.

Users of the Xbox One reported that the console's disc drive made a loud noise when they tried to insert a disc and in some cases couldn't read discs at all. Microsoft responded by offering a replacement console and a free game download to anyone affected by the problem.

The giant ball of ice and dust was initially declared dead when it failed to re-emerge from behind the star with the expected brightness.

All that could be seen was a dull smudge in space telescope images - its nucleus and tail assumed destroyed.

But recent pictures have indicated a brightening of what may be a small fragment of the comet.

Astronomers admit to being surprised and delighted, but now caution that anything could happen in the coming hours and days.

This remnant of Ison could continue to brighten, or it could simply fizzle out altogether.

"We've been following this comet for a year now and all the way it has been surprising us and confusing us," said astrophysicist Karl Battams, who operates the US space agency-funded Sungrazing Comets Project.

"It's just typical that right at the end, when we said, 'yes, it has faded out, it's died, we've lost it in the Sun', that a couple of hours later it should pop right back up again," he told BBC News.

The European Space Agency (Esa), too, which had been among the first organisations to call the death of Ison, has had to re-assess the situation. A small part of the nucleus may be intact, its experts say. How much of the once 2km-wide hunk of dirty ice could have survived is impossible to say.

Passing just 1.2 million km above the surface of the Sun would have severely disrupted Ison. Its ices would have vaporized rapidly in temperatures over 2,000C. And the immense gravity of the star would also have pulled and squeezed on the object as it tumbled end over end.

Karl Battams said: "We would like people to give us a couple of days, just to look at more images as they come from the spacecraft, and that will allow us to assess the brightness of the object that we're seeing now, and how that brightness changes.

"That will give us an idea of maybe what the object is composed of and what it might do in the coming days and weeks."

Whatever happens next, comets are going to be a big feature in the news over the next year.

The zone covers territory claimed by China, Japan, Taiwan and South Korea.

China said last week that all aircraft crossing through the zone must file flight plans and identify themselves or face "defensive emergency measures".

The US, Japan and South Korea say they have since defied the ruling and flown military aircraft in the area. The air defence identification zone (ADIZ) covers a vast area of the East China Sea and includes a group of islands which are claimed by Japan, China and Taiwan.

South Korea claims ownership of a submerged rock, known as Ieodo, within the zone.

The establishment of the ADIZ has caused widespread anger, with the US calling it a "destabilising attempt to alter the status quo in the region".

There are fears that the increasing tension and militarisation of the region could escalate into an unplanned military incident.

'Firm but calm' On Thursday, China had announced it was deploying warplanes in the area as a "defensive measure" and to carry out routine surveillance.

Then on Friday, Air Force spokesman Col Shen Jinke said Chinese warplanes had been scrambled that morning to identify two US surveillance aircraft and 10 Japanese planes - including early warning aircraft, surveillance aircraft and fighter jets - crossing through the ADIZ, state media reports.

Col Jinke made no reference to whether any further action was taken by any of the aircraft.

Earlier, Foreign Ministry spokesman Qin Gang said China had a right to patrol the region and that it the ADIZ was not aimed at any specific country. It's absolutely a measure designated to exercise the right of defence effectively," he told a regular briefing.

"If some worry has emerged about the situation, it's agitated by some individual countries."

If maritime disputes existed, China wanted to solve them through "peaceful means via friendly negotiation," state news agency Xinhua quoted him as saying.

Japanese Prime Minister Shinzo Abe said on Friday that Japan would respond "firmly but in a calm manner" to China's move, the Kyodo news agency reports. Foreign Minister Fumio Kushida said the issue would be discussed with US Vice-President Joe Biden, who is due to begin a three-day visit to Japan on Monday.

The disputed group islands in the zone - known as Senkaku in Japan and Diaoyu in Chinese - are uninhabited, but have been the subject of rising tensions in recent years.

Another major outage of glitch-ridden HealthCare.gov could spell more political trouble for the president, who was forced to apologize for the botched rollout and admit burdening Democratic Party allies in their bids for re-election to Congress in 2014.

If the website does not work on Saturday's deadline, that could turn off millions of uninsured Americans, especially young and healthy consumers whose participation in the new insurance exchanges are critical for keeping costs in check.

Democratic leaders in Congress might also find it necessary to extend open enrollment beyond the March 31 deadline and delay fines mandated by the law for people who do not have insurance by that date - a prospect that insurers warn would destabilize the market.

Obama officials are confident that this second coming of HealthCare.gov will be much improved from the October 1 debut. Millions of people looked into the website in its first month, but only about 27,000 cleared the gauntlet of technical obstacles to sign up for insurance.

The portal is the gateway for health insurance plans in 36 states under the Patient Protection and Affordable Care Act, commonly called Obamacare, which was passed in 2010. It is intended to move the United States closer to universal care by subsidizing insurance sold by the private sector for less affluent families.

Officials have said that by Saturday the website will be able to load quickly and work accurately for at least 80 percent of users. They have said it will be able to handle 50,000 simultaneous visitors, for a daily total of about 800,000, twice the capacity seen even on Wednesday before a final flurry of hardware and software fixes over the Thanksgiving holiday.

And officials have warned that the website will still suffer some delays and outages in the weeks to come. To help consumers left hanging when traffic exceeds capacity, they have created a new "queuing system" to tell consumers when to come back.

Short of a major outage, it may be difficult to immediately measure the administration's success because officials only release enrollment figures once a month. That will make anecdotes from consumers and enrollment groups all the more important.

The move follows months of negotiations and was learned from sources close to the deal on Friday after being kept secret. Baghdad says any independent Kurdish oil exports are illegal and that it has the sole authority to manage Iraqi oil.

For energy-hungry Turkey, dependent on imports for almost all of its needs, exploiting Iraqi Kurdistan's rich hydrocarbon resources will help diversify its energy supplies and reduce the country's ballooning $60 billion energy bill.

Ankara's close partnership with Iraqi Kurds is historic and to many, marks the beginning of a new era, given the decades-long fight with Kurdish militants on Turkish soil that has claimed more than 40,000 lives.

The deal came in the early hours of a frosty Wednesday morning in Ankara, and was signed during a three-hour meeting between Kurdistan Regional Government (KRG) Prime Minister Nechirvan Barzani and Turkish Prime Minister Tayyip Erdogan.

"This is the most comprehensive energy deal in Turkey's history," a source close to the matter said. "But due to political sensitivities, both sides are taking their time to announce it."

Neither the Turkish prime minister's office nor the energy ministry confirmed the signatures following Wednesday's meeting. On Friday, the energy ministry declined to comment.

Officials in the office of Iraq's deputy prime minister for energy, Hussain al-Shahristani, were not immediately available for comment.

Sources say neither the Turks nor the Kurds wanted to pop the champagne while efforts to get the Iraqi central government on board continue, even though Baghdad can do nothing to stop the process.

Baghdad has long claimed the sole authority to manage Iraqi oil and says Kurdish efforts towards oil independence could lead to the break-up of Iraq. Turkey's courtship of Kurds has also raised concern in Washington.

But Turkey has repeatedly said it respects Iraq's sensitivities over territorial integrity and that increasing oil revenues will help the whole of Iraq.

Protesters burst into the army base Bangkok's historic quarter, waving flags and blowing whistles. In another district, about 1,000 people massed outside Yingluck's ruling party headquarters, shouting "get out".

The invasion of army headquarters deepened a conflict broadly pitting the urban middle class against the mostly rural supporters of Yingluck and her brother, Thaksin Shinawatra, a former prime minister who was ousted in a 2006 coup and who remains central to Thailand's eight years of on-off turmoil.

The demonstrators left the headquarters peacefully after a few hours and late on Friday, protest leader Suthep Thaugsuban told his supporters to increase the pressure and target main state buildings on Sunday, including the headquarters of city and police, four ministries and Government House, Yingluck's offices.

"Don't wait for anyone. Every heart that loves this country must stand up together and execute our mission as one," Suthep told a crowd of 7,000 massed outside a state office complex.

"On Sunday, brothers and sisters, we will announce our victory and our defeat of the Thaksin regime."

The protesters accuse Yingluck of abusing her party's parliamentary majority to push through laws that strengthen the behind-the-scenes power of her populist self-exiled, billionaire brother. They have rejected her calls for talks.

Although the army moved its main command centre to a military camp in Bangkok's northern suburbs three days ago, the siege of its grounds by protesters is deeply symbolic and highlights the military's pivotal role in a country that has seen 18 successful or attempted coups in the past 80 years.

After forcing open the compound's gates, protesters swarmed inside, demanding the generals choose sides as hundreds of soldiers watched from the balconies of the 19th-century cream-colored building.

CHOOSE A SIDE

"We want the head of Thailand's armed forces to choose whether they stand by the government or with the people," Uthai Yodmanee, a protest leader, said from the back of a truck.

Yingluck has courted the powerful army, which asked protesters not to pressure it to take sides and to consider revered King Bhumibol Adulyadej, who turns 87 on December 5.

"We are ready to help the Thai people if there is violence. We hope all sides will unite and not use the army as a tool," army chief Prayuth Chan-ocha said in a statement. "It might make His Majesty feel uneasy if Thais fight among themselves."

It raises the prospect that taking cholesterol-lowering drugs called statins could prevent cancer.

The work, published in the journal Science, helps explain why obesity is a major risk factor for the disease.

However, cancer charities cautioned that it was too soon to advise women to take statins.

Obesity has been linked with many cancers including those of the breast, bowel and womb. The fat in overweight people can pump out hormones, such as oestrogen, which drive the growth of cancers.

A team at Duke University Medical Centre, in the US, showed that cholesterol was having a similar effect.

Cholesterol is broken down by the body into 27HC, which can mimic oestrogen and produce the same effect as the hormone in some tissues.

Experiments on mice showed that a high fat diet increased levels of 27HC in the blood and led to tumours that were 30% larger than in mice on a normal diet.

Tumours were also more likely to spread. And human breast cancer tissue grew more quickly in the laboratory when it was fed 27HC.

One of the researchers Prof Donald McDonnell said: "A lot of studies have shown a connection between obesity and breast cancer, and specifically that elevated cholesterol is associated with breast cancer risk, but no mechanism has been identified.

"What we have now found is a molecule - not cholesterol itself, but an abundant metabolite of cholesterol - called 27HC that mimics the hormone oestrogen and can independently drive the growth of breast cancer."

Treatment The researchers say their findings raise the prospect that lowering cholesterol can lower the risk of breast cancer developing.

Statins are already taken by millions of people to cut the risk of heart disease. However, studies have already suggested statins can cut the risk of breast cancer.

A healthier diet is another way to cut levels of cholesterol in the bloodstream.

Dr Hannah Bridges, from leading charity Breakthrough Breast Cancer, says: "Up until now research into the links between cholesterol levels, use of statins and breast cancer risk has been inconclusive.

"The results from this early study are promising and if confirmed through further research could increase our understanding of what causes some breast cancers to develop."

Dr Emma Smith, from Cancer Research UK, said: "This study is intriguing as it shows for the first time a direct link between cholesterol and breast cancer in mice - but it's too early to say how this knowledge might help tackle breast cancer in the future.

Apptricity, based in Texas, has provided logistics programs to the army since 2004.

The company said it had discovered last year the software had been installed on many more machines than had been licensed.

The Department of Justice has not commented on the settlement.

The Dallas Morning News reported a DoJ spokeswoman had confirmed the agreement, but would not give more details.

Apptricity's software allows the military to track the movements of soldiers as well as key supplies.

It has also been used during relief efforts, most notably in Haiti following the 2010 earthquake.

According to court documents filed in 2012, the deal with the military meant up to 500 named users could access the software.

Presentation revelation

Apptricity later estimated that 9,000 users were accessing the program, in addition to the 500 that had been paid for.

The unauthorised copying only came to light after a US Army official mentioned "thousands" of devices running the software during a presentation on technology.

Apptricity called for $224m (£137m) to be paid to cover costs.

The settlement of $50m falls some way short - but in a statement the company said Apptricity would spend the sum on expanding the company.

"Apptricity is now incredibly energised to use the settlement resolution as a catalyst for aggressive investment in our team, our solutions and our untapped market opportunities," said Randy Lieberman, Apptricity's chief financial officer.

In recent years, the US government has stepped up efforts to combat piracy, announcing a wide-ranging strategy for clamping down in 2010.

Publisher 505 Games apologised and said refunds would be given to those who had purchased the title for PC.

The game had already been delayed by several months, and will now be abandoned entirely.

One games journalist said it was "clearly unfinished" and "didn't even have an animation for catching".

Videogamer.com editor-in-chief Simon Miller said such a botched launch was unprecedented.

"They were never going to get away with it," he told the BBC.

"Usually if a game is pulled they delay it - but for them to say they can't do this at all, it must have been an absolute nightmare in development." The game was made available on Valve's Steam online store on 22 November.

Future releases on Xbox 360, PlayStation 3 and Wii U were never given a firm date. The title had originally been scheduled for release to coincide with the Ashes test that took place this summer.

Footage of glitches in the game were quickly uploaded to YouTube. One clip, uploaded by PlanetCricket.net editor Matt Whitehorn, showed fielders in a state of confusion, dancing around and throwing the ball in random directions.

Misplaced assurances 505 Games blamed the lacklustre quality on Australian-based Trickstar Games - the developer contracted to make the game.

"The development of Ashes Cricket 2013 has been fraught with challenges almost from the outset," 505 Games said.

"The chosen developer, even with their many years of cricket game development experience, was unable to overcome the unexpected challenges that the chosen game engine threw up, even with multiple extensions to the development schedule.

"At the start of the project, 505 Games received all assurances from the developer that the engine was up to the task of creating a dynamic, cutting-edge cricket game for the modern age across multiple platforms, and unfortunately those assurances were found to be misplaced."

The company went on to apologise to the England and Wales Cricket Board (ECB) and Cricket Australia, as well as various sponsors involved in the series.

It added: "Our deepest apologies, however, are reserved for the fans of cricket and cricket games worldwide."

The movement of a tiny magnet in a tongue piercing is detected by sensors and converted into commands, which can control a range of devices.

The US team said it was harnessing the tongue's "amazing" deftness.

The development is reported in the journal Science Translational Medicine.

The team at the Georgia Institute of Technology made the unlikely leap from body art to wheelchairs because the tongue is so spectacularly supple.

A large section of the brain is dedicated to controlling the tongue because of its role in speech. It is also unaffected by spinal cord injuries that can render the rest of the body paralysed, tetraplegic, as it has its own hotline to the brain.

"We are tapping in to the inherent capabilities of the tongue, it is such an amazing part of the body," Dr Maysam Ghovanloo told the BBC.

A lentil-sized piercing in the tongue produces a magnetic field, which changes as the tongue moves. Sensors on the cheeks can then detect the precise position of the piercing.

In the trial, on 23 able-bodied people and 11 with tetraplegia, six positions in the mouth were programmed to control a wheelchair or a computer such as touching the left cheek to turn the chair to the left. On average, people with tetraplegia were able to perform tasks three times as fast and with the same level of accuracy as with the other technologies available.

The researchers believe they will be able to have a command for every tooth in the mouth and that by using combinations of tongue positions would be able to develop an "unlimited" number of instructions.

These could dial a phone, change the channel on the television or even type. Dr Ghovanloo said: "People will be able to do more and do more things more effectively."

He said patients were "all very cool with it" but some older people did not take part in the trial due to tongue piercing reticence.

At the moment the device is limited to university laboratories. The team is trying to fit the sensors into a dental brace to make it more stable on the road, get it approved by the US regulators and come up with a way of getting the expensive kit into the hands of patients.

Dr Mark Bacon, the director of research at the charity Spinal Research, said the ultimate goal remained regenerating the spinal cord but living aids were "needed now".

U.S. Defense Secretary Chuck Hagel assured his Japanese counterpart in a phone call that the two nations' defense pact covered the small islands where China established a new airspace defense zone last week and commended Tokyo "for exercising appropriate restraint," a Pentagon spokesman said.

China's declaration raised the stakes in a territorial standoff between Beijing and Tokyo over the area, which includes the tiny uninhabited islands known as the Senkaku in Japan and the Diaoyu in China.

The United States defied China's demand that airplanes flying near the islands identify themselves to Chinese authorities, flying two unarmed B-52 bombers over the islands on Tuesday without informing Beijing.

It was a sharp reminder to China that the United States still maintains a large military presence in the region despite concerns among U.S. allies that President Barack Obama's "pivot to Asia" strategy has borne little fruit.

In a previously announced trip, Vice President Joe Biden will visit China, Japan and South Korea next week. He will seek to ease tensions heightened by China's declaration, senior administration officials said.

Washington does not take a position on the sovereignty of the islands but recognizes that Tokyo has administrative control over them and the United States is therefore bound to defend Japan in the event of an armed conflict.

Some experts say the Chinese move was aimed at eroding Tokyo's claim to administrative control over the area.

China's Defense Ministry said it had monitored the U.S. bombers on Tuesday. A Pentagon spokesman said the planes had not been observed or contacted by Chinese aircraft.

'FRICTION AND UNCERTAINTY'

In a conference call with reporters, senior U.S. administration officials said China's declaration raised serious concerns about its intentions.

"It causes friction and uncertainty, it constitutes a unilateral change to the status quo in the region, a region that's already fraught. And it increases the risk of miscalculation and accidents," one of the officials said.