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Researchers put six grey seals in a specially built tank to work out why they don’t drown – and discovered something unexpected

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Human freedivers can descend to significant depths on just one lungful of air. To do this they massively overbreathe beforehand to clear their systems of as much carbon dioxide (CO₂) as possible. This is the gas that triggers the normal urge to breathe when we hold our breath. But the technique doesn’t always work. Freedivers can black out underwater and must have teams of scuba divers on standby to rush them back to the surface.

Seals can dive to great depths for long periods of time, chasing their fishy prey. So why do they never seem to end up unconscious? This question intrigued marine ecologist Chris McKnight and his colleagues at the University of St Andrews.

To find out, they lined up six grey seals, temporarily taken from the wild, in a specially built tank. This was an enclosed underwater home with a feeding area and a domed breathing chamber at one end. The seals could forage for as long as they liked in the water and then surface to take a breath in the chamber, rather like emerging into the air through a hole in an ice sheet.

One of the seals from the study, Oisin. Credit: Sea Mammal Research Unit

The scientists filled the breathing chamber air with different combinations of oxygen and CO₂, starting with normal air at 21 per cent oxygen and 0.04 per cent CO₂. Gradually they switched to higher concentrations of oxygen and then lower, followed by higher and lower concentrations of CO₂. They measured how long the seals’ feeding trips lasted while breathing each of the air mixes.

The expectation was that high-oxygen air would mean the seals stayed underwater longer. High CO₂ levels should make the dives shorter, they thought, as with humans when high CO₂ levels in their blood activate the need to breathe. To their surprise, the amount of CO₂ had no effect on the length of time the seals took between breaths. But low oxygen levels certainly did.

Their conclusion was that a seal’s brain monitors the amount of oxygen in its blood, rather than the levels of CO₂, and the animals make their own decisions on how long to stay underwater based on that information. Instead of their bodies being governed by an involuntary reaction to the amount of CO₂ in their systems, seals can judge when their oxygen levels need topping up and make their way to the surface in a controlled and timely manner. Therefore, they never risk drowning.

More amazing wildlife stories from around the world



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Treasury secretary says countries without trade deals will see tariffs ‘boomerang’ to April rates by Aug. 1

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WASHINGTON — Treasury Secretary Scott Bessent said Sunday that the U.S. will revert to steep country-by-country tariff rates at the beginning of August, weeks after the tariff rate pause is set to expire.

“President Trump’s going to be sending letters to some of our trading partners saying that if you don’t move things along, then on Aug. 1, you will boomerang back to your April 2 tariff level,” Bessent said in an interview on CNN’s “State of the Union.” “So I think we’re going to see a lot of deals very quickly.”

President Donald Trump had originally set a 90-day deadline — set to expire Wednesday — for countries to renegotiate the eye-watering tariff levels he laid out in his April 2 “Liberation Day” speech. He paused those rates a week later, while setting a new 90-day deadline to renegotiate them.

That deadline was set to expire Wednesday.

CNN host Dana Bash responded to Bessent on Sunday, saying, “There’s basically a new deadline,” prompting Bessent to push back.

“It’s not a new deadline. We are saying this is when it’s happening,” Bessent said. “If you want to speed things up, have at it. If you want to go back to the old rate, that’s your choice.”

On Friday, Trump, too, referred to an Aug. 1 deadline, raising questions about whether the July 9 deadline still stands. A White House spokesperson did not provide a comment when asked to clarify whether the April 2 tariff rates would resume July 9 or Aug. 1.

The president has recently given shifting descriptions of how firm the July 9 deadline is, saying at the end of June, “We can extend it, we can shorten it,” only to double down on it several days later, saying he was not thinking about extending it.

Shortly after midnight Friday, Trump referred to an Aug. 1 timeline, telling reporters that the April 2 tariff rates would resume at the start of August.

Asked whether the U.S. would be flexible with any countries about on the July 9 deadline, Trump said, “Not really.”

“They’ll start to pay on Aug. 1,” he added. “The money will start to come into the United States on Aug. 1, OK, in pretty much all cases.”

Trump said Friday that the administration would start sending letters to countries, adding, “I think by the 9th they’ll be fully covered.”

“They’ll range in value from maybe 60% or 70% tariffs to 10% and 20% tariffs, but they’re going to be starting to go out sometime tomorrow,” Trump said overnight on Friday. “We’ve done the final form, and it’s basically going to explain what the countries are going to be paying in tariffs.”

Trump said in a Truth Social post late Sunday evening that tariff letters would be delivered starting at noon on Monday.

Bessent also said Sunday that “many of these countries never even contacted us.”

Tariffs are paid by importers — which can pass on part or all of the costs to consumers — and not necessarily by entities in the goods’ country of origin.

The White House had initially projected confidence that dozens of countries would try to make deals. White House trade adviser Peter Navarro said on NBC News’ “Meet the Press” in April that “we’ve got 90 deals in 90 days possibly pending here.” Late last month, Trump said, “Everybody wants to make a deal,” and after he announced sweeping tariffs on April 2, he said countries were “calling us up, kissing my a–.”

“They are,” he said in April. “They are dying to make a deal. ‘Please, please, sir, make a deal. I’ll do anything.’”

The renewed uncertainty is likely to further upset markets, where stock futures went lower Friday after Trump mentioned the country letters. Stocks have returned to all-time highs in part due to the lull in tariff news.

So far, Trump has imposed higher import duties on autos and auto parts, steel and aluminum, and goods from China and Vietnam.



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Windows 11 has finally overtaken Windows 10 as the most used desktop OS

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Microsoft has finally crossed an important milestone for Windows 11, months ahead of Windows 10’s end of support cutoff date. Stat Counter, spotted by Windows Central, now lists Windows 11 as the most used desktop operating system nearly four years after its release, with 52 percent of the market, compared to 44.59 percent for Windows 10.

Windows 11 became the most popular OS for PC gaming in September, but overall adoption had still been lagging behind Windows 10 until now. Leaked data in October 2023 also revealed Windows 11 was used by more than 400 million devices at the time, a slower adoption pace than Windows 10 — which took just a year to reach 400 million devices compared to Windows 11’s two year period.

Part of the slow adoption is down to Windows 11’s hardware requirements. While Microsoft offered a free upgrade to Windows 10 users, millions of machines have been left behind due to stricter CPU and security requirements. Microsoft has been trying to convince the owners of these machines to upgrade their hardware in order to get Windows 11, sometimes with a full-screen prompt.

Windows 10 is due to reach end of support on October 14th, and Microsoft recently revealed it would give away a free year of extra security updates to consumers if they were willing to enable Windows Backup and sync their Documents folder to OneDrive. If you don’t want to do this, you’ll have to pay $30 for a year of updates, or redeem 1,000 Microsoft Reward points.



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Israel says it struck Houthi ports and seized cargo ship in Yemen

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Yang Tian & David Gritten

BBC News

Mohammed Hamoud/Getty Images The Galaxy Leader Vessel is seen on the Red Sea coast off Hudaydah, on May 12, 2024. Mohammed Hamoud/Getty Images

Israel says the Galaxy Leader, a ship previously hijacked by Houthi rebels, was among the targets

The Israeli military says it has carried out air strikes on Houthi-controlled areas of Yemen in response to repeated missile and drone attacks on Israel.

The military said the targets were the Red Sea ports of Hudaydah, Ras Issa and al-Salif, a nearby power station, and the cargo ship Galaxy Leader. The ship, hijacked by the Houthis in November 2023, was being used to monitor international shipping, according to the military.

The Houthis’ military spokesman said the Iran-backed group’s air defences “successfully” confronted the Israeli attack. There were no reports of any casualties.

Following the strikes, two missiles were launched from Yemen towards Israel, according to the Israeli military.

Sirens were triggered in several areas of the occupied West Bank and southern Israel. The military said it was reviewing its attempt to intercept the missiles.

Houthi-run Al-Masirah TV reported that the strikes on Sunday night hit the ports as well as the Ras Kanatib power station, north of Hudaydah, but it provided no further details on damage or casualties.

The Israeli military said about 20 fighter jets carried out the operation “in response to the repeated attacks by the Houthi terrorist regime against the State of Israel, its civilians, and civilian infrastructure, including the launching of UAVs and surface-to-surface missiles toward Israeli territory”.

It alleged that the ports were used to transfer weapons from Iran and that Houthi forces had installed a radar system on the Bahamas-flagged Galaxy Leader “to track vessels in the international maritime arena to facilitate further terrorist activities”.

The Israeli military said the Ras Kanatib power plant, which supplies electricity to the nearby cities of Ibb and Taizz, was used to power Houthi military operations.

Israeli Defence Minister Israel Katz warned that the Houthis “will continue to pay a heavy price for their actions”.

“The fate of Yemen is the same as the fate of Tehran. Anyone who tries to harm Israel will be harmed, and anyone who raises a hand against Israel will have their hand cut off,” he said in a post on X.

Houthi military spokesman Yahya Sarea said in a statement on Monday that the group’s air defences “succeeded in confronting the Zionist aggression against our country and thwarting its plan to target a number of Yemeni cities”.

“In retaliation to this aggression, and in continuation of triumphing for the oppressed Palestinian people, the missile and UAV forces carried out a joint military operation using 11 missiles and drones,” he added, identifying the targets as Tel Aviv’s Ben Gurion airport, the ports of Ashdod and Eilat, and a power station in Ashkelon.

Sarea also declared that the Houthis were “fully prepared for a sustained and prolonged confrontation” with Israel.

Getty Images Yemen's port city of Hudaydah after it was struck by Israel on 6 May 2025.Getty Images

Yemen’s port city of Hudaydah after it was struck by Israel in May 2025

The Houthis have controlled much of north-western Yemen since 2014, when they ousted the internationally-recognised government from the capital, Sanaa, and sparked a devastating civil war.

Since the start of the war between Israel and Hamas in Gaza in October 2023, the Houthis have regularly launched missiles at Israel and attacked commercial ships in the Red Sea and Gulf of Aden, saying they are acting in solidarity with the Palestinians.

They have so far sunk two vessels, seized a third – the Galaxy Star – and killed four crew members. The 25-strong crew of Galaxy Leader were released in January 2025.

In May, the Houthis agreed a ceasefire deal with the US following seven weeks of intensified US strikes on Yemen in response to the attacks on international shipping.

However, the group said the agreement did not include an end to attacks on Israel, which has conducted multiple rounds of retaliatory strikes on Yemen.

In May, Israeli navy ships struck targets in Hudaydah, which is the main entry point for food and other humanitarian aid for millions of Yemenis.

As well as claiming to have fired at Ben Gurion airport, the Houthis also said they targeted a Liberian-flagged, Greek-operated bulk carrier Magic Seas in the Red Sea.

The UK Maritime Trade Operations (UKMTO) agency said the ship was 51 nautical miles (94km) first attacked with gunfire and self-propelled grenades fired from multiple small boats. Armed security teams on board returned fire, it added.

Maritime security firm Ambrey said the Magic Seas was later also targeted with four unmanned surface vehicles, or sea drones, and missiles. Two of the drones hit the port side of the vessel, damaging it cargo and causing a fire, it added.

The UKMTO said the crew were safe after being rescued by a passing merchant vessel.



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