SpaceX had just conducted yet another static fire test of the Raptor engine in its Starship SN4 prototype launch vehicle on Friday when the test vehicle exploded on the test stand in Boca Chica, Texas. TechCrunch reports: This was the fourth static fire test of this engine on this prototype, so it's unclear what went wrong vs. other static fire attempts. This was a test in the development of Starship, a new spacecraft that SpaceX has been developing in Boca Chica. Eventually, the company hopes to use it to replace its Falcon 9 and Falcon Heavy rocket, but Starship is still very early in its development phase, whereas those vehicles are flight-proven, multiple times over.

SpaceX had just secured FAA approval to fly its Starship prototype for short, suborbital test flights earlier this week. The goal was to fly this SN4 prototype for short distances following static fire testing, but that clearly won't be possible now, as the vehicle appears to have been completely destroyed in the explosion following Friday's test, as you can see in the stream from NASASpaceflight.com. The explosion occurred around 1:49 PM local time in Texas, roughly two minutes after it had completed its engine test fire.

A reader shares a report from Science Magazine: The end of the Devonian period, 359 million years ago, was an eventful time: Fish were inching out of the ocean, and fernlike forests were advancing on land. The world was recovering from a mass extinction 12 million years earlier, but the climate was still chaotic, swinging between hothouse conditions and freezes so deep that glaciers formed in the tropics. And then, just as the planet was warming from one of these ice ages, another extinction struck, seemingly without reason. Now, spores from fernlike plants, preserved in ancient lake sediments from eastern Greenland, suggest a culprit: The planet's protective ozone layer was suddenly stripped away, exposing surface life to a blast of mutation-causing ultraviolet (UV) radiation.

Just as the extinction set in, the spores became misshapen and dark, indicating DNA damage, John Marshall, a palynologist at the University of Southampton, and his co-authors say in a paper published in Science Advances. It's evidence, he says, that "all of the ozone protection is gone." Scientists have long believed -- at least before humanity became a force for extinction -- that there were just two ways to wipe out life on Earth: an asteroid strike or massive volcanic eruptions. But 2 years ago, researchers found evidence that in Earth's worst extinction -- the end-Permian, 252 million years ago -- volcanoes lofted Siberian salt deposits into the stratosphere, where they might have fed chemical reactions that obliterated the ozone layer and sterilized whole forests. Now, spores from the end-Devonian make a compelling case that, even without eruptions, a warming climate can deplete the ozone layer, says Lauren Sallan, a paleobiologist at the University of Pennsylvania. "Because the evidence is so strong, it will make people rethink other mass extinction events."

Chinese scientists in recent days said they had ruled out both a laboratory and an animal market in the city of Wuhan as possible origins of the coronavirus pandemic, in their most detailed pushback to date against allegations from U.S. officials and others over what might have sparked it. From a report: The director of the Wuhan Institute of Virology, at the center of allegations around a potential laboratory accident, Wang Yanyi, over the weekend told China Central Television that the coronavirus was significantly different from any live pathogen that has been studied at the institute and that there therefore was no chance it could have leaked from there. Separately, China's top epidemiologist said Tuesday that testing of samples from a Wuhan food market, initially suspected as a path for the virus's spread to humans, failed to show links between animals being sold there and the pathogen.

Gao Fu, director of the Chinese Center for Disease Control and Prevention, said in comments carried in Chinese state media, "It now turns out that the market is one of the victims." The comments, aimed at countering what Beijing perceives as efforts from top U.S. officials to focus solely on China, are unlikely to pacify critics. The Chinese officials didn't address fundamental issues, such as widespread evidence that China initially covered up the extent of the outbreak. In their calls for more global scientific collaboration to track the source of the virus, they also stopped short of endorsing widespread scientific belief that the coronavirus originated in China.

Jon Hamilton, reporting for NPR: Mounting evidence suggests the coronavirus is more common and less deadly than it first appeared. The evidence comes from tests that detect antibodies to the coronavirus in a person's blood rather than the virus itself. The tests are finding large numbers of people in the U.S. who were infected but never became seriously ill. And when these mild infections are included in coronavirus statistics, the virus appears less dangerous. "The current best estimates for the infection fatality risk are between 0.5% and 1%," says Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security.

That's in contrast with death rates of 5% or more based on calculations that included only people who got sick enough to be diagnosed with tests that detect the presence of virus in a person's body. And the revised estimates support an early prediction by Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and a leading member of the White House coronavirus task force. In an editorial published in late March in The New England Journal of Medicine, Fauci and colleagues wrote that the case fatality rate for COVID-19 "may be considerably less than 1%." But even a virus with a fatality rate less than 1% presents a formidable threat, Rivers says. "That is many times more deadly than seasonal influenza," she says. The new evidence is coming from places such as Indiana, which completed the first phase of a massive testing effort early in May. Further reading: Antibody Tests and Accuracy Issues Leave Some Americans With More Questions Than Answers.

A global natural experiment examines the time warp of life under quarantine. From a report: In April Jenny Rappaport sat down to inspect her calendar because she could not tell how many days had passed since New Jersey's stay-at-home order took effect. Before COVID-19, her life had structure and a pace, and she knew the day of the week without giving it a second thought. The pandemic has changed all of that. Several research groups have taken advantage of this unplanned natural experiment to gauge the psychological impacts of time distortions and, in turn, their effects on mental health. Psychologists know that time sense links to well-being. Its perceived slower passage can represent signs of depression or post-traumatic stress disorder (PTSD).

Rappaport's feelings jibe with the findings of preliminary studies. Overall, people seem to be experiencing time more slowly, according to data that are beginning to be compiled. In a not yet peer-reviewed preprint paper, Sylvie Droit-Volet, a time perception researcher at the University of Clermont Auvergne in France, and her colleagues show that people there report the clock moving more slowly during the lockdown. The researchers also document feelings of sadness and boredom and tie them to the overall feeling of deceleration. "Their findings directly support the emotional connection with time perception," says Philip Gable of the University of Alabama. He is also using survey data to examine how people across the U.S. experience time during the pandemic. "It's a societal event that's going to have a profound psychological influence on us," Gable says, adding that the temporal shift is an integral part of our feelings about what is happening. He plans to collect data over the next nine months, but so far has found evidence that the everyday tempo now lags. Nearly 50 percent of people experienced time dragging during March, whereas about 24 percent perceived it to be speeding up.

The hits came this week in rapid succession: A cyclone slammed into the Indian megacity of Kolkata, pounding rains breached two dams in the Midwestern United States, and on Thursday came warning that the Atlantic hurricane season could be severe. It all served as a reminder that the coronavirus pandemic, which has killed 325,000 people so far, is colliding with another global menace: a fast-heating planet that acutely threatens millions of people, especially the world's poor. From a report: Climate change makes extreme weather events more frequent and more intense. Now, because of the pandemic, they come at a time when national economies are crashing and ordinary people are stretched to their limits. Relief organizations working in eastern India and Bangladesh, for instance, say the lockdown had already forced people to rely on food aid by the time the storm, Cyclone Amphan, hit. Then, the high winds and heavy rains ruined newly sown crops that were meant to feed communities through next season. "People have nothing to fall back on," Pankaj Anand, a director at Oxfam India, said in a statement Thursday. The worst may be yet to come.

Several other climate hazards are looming, as the coronavirus unspools its long tail around the world. They include the prospect of heat waves in Europe and South Asia, wildfires from the western United States to Europe to Australia, and water scarcity in South America and Southern Africa, where a persistent drought is already deepening hunger. And then there's the locusts. Locusts. Abnormally heavy rains last year, which scientists say were made more likely by the long-term warming of the Indian Ocean, a hallmark of climate change, have exacerbated a locust infestation across eastern Africa. Higher temperatures make it more inviting for locusts to spread to places where the climate wasn't as suitable before -- and in turn, destroy vast swaths of farmland and pasture for some of the poorest people on the planet.

A third of Americans are showing signs of clinical anxiety or depression (alternative source), Census Bureau data shows, the most definitive and alarming sign yet of the psychological toll exacted by the coronavirus pandemic. The Washington Post reports: When asked questions normally used to screen patients for mental health problems, 24 percent showed clinically significant symptoms of major depressive disorder and 30 percent showed symptoms of generalized anxiety disorder. The findings suggest a huge jump from before the pandemic. For example, on one question about depressed mood, the percentage reporting such symptoms was double that found in a 2014 national survey.

How Americans responded to the question "How often have you been bothered by feeling down, depressed, or hopeless?" Someone who answered "several days" or "more than half the days" would need to show other symptoms to screen positive for clinical depression. The 2013-2014 study reflects symptoms over a two-week period, while the 2020 survey reflects symptoms over a one-week period. [...] Some groups have been hit harder than others. Rates of anxiety and depression were far higher among younger adults, women and the poor. The worse scores in young adults were especially notable, given that the virus has been more likely to kill the elderly or leave them critically ill.

SpaceX is set to mark a huge milestone in its own company history, with a first-ever crewed spaceflight set to take off from Cape Canaveral in Florida later today. From a report: The mission is Commercial Crew Demo-2, the culmination of its Crew Dragon human spacecraft development program, which will carry NASA astronauts Doug Hurley and Bob Behnken to the International Space Station. The launch is currently set to take off from Kennedy Space Center at 4:33 p.m. EDT (1:33 p.m. PDT), though that'll depend on weather conditions. Those haven't been looking too favorable over the past few days, but SpaceX and NASA have said they could make the call as late as around 45 minutes prior to the planned launch time about whether to delay. If today's attempt is scrubbed, there are backup opportunities on the schedule for May 30 and May 31.

UPDATE: The launch has been scrubbed due to weather conditions. NASA and SpaceX will reattempt on Saturday.

sciencehabit writes: Roughly half of the "normal" matter in the universe -- the stuff that makes up stars, planets, and even us -- exists as mere wisps of material floating in intergalactic space, according to cosmologists. But astronomers had no good way to confirm that, until now. A new study has used fast radio bursts (FRBs) -- powerful millisecondslong pulses of radio waves coming from distant galaxies -- to weigh intergalactic matter, and the results match up with predictions. "Using FRBs as a probe has been an exciting prospect for a while," says astronomer Paul Scholz of the University of Toronto, who was not involved with the work. "Now that we've built up a sample of local FRBs, we're starting to be able to do this. It's certainly exciting." Over the past few decades, cosmologists have compiled an inventory of the stuff that makes up the universe. Some 68% is dark energy, a mysterious force accelerating the universe's expansion. Another 27% is clumps of dark matter that hold galaxies together. Just 5% is so-called normal matter.

Cosmologists know how much normal matter there should be; they can calculate it from how much the big bang should have produced and from the microwave ripple of this cosmic event that still echoes through space. But they can only see about half of it glowing as galaxies and dense gas clouds. The rest, a rarified, intergalactic gas of just one or two atoms in the volume of a typical office room, has been almost impossible to detect. That was until the first FRB burst on the scene in 2007. Because these sporadic blasts are so bright and short, FRBs were originally thought to come from an instrumental glitch, or a source on Earth. (Some early "FRBs" were found to come from a microwave oven at an observatory.) But as detections of FRBs piled up, astronomers realized they were coming from distant corners of the universe. Pinpointing them was difficult because of their rarity: Observers had to be pointing in the exact right direction to catch one, and they wouldn't have time to focus other scopes on the source. These days, telescopes that view large portions of the sky continuously are bagging more FRBs.

Anthony Fauci told CNN Wednesday that the scientific data "is really quite evident now about the lack of efficacy" of hydroxychloroquine as a coronavirus treatment. From a report: The comments came in response to news that France on Wednesday banned the use of hydroxychloroquine to treat the virus, after a large retrospective study in The Lancet found an increased risk of heart problems and death among coronavirus patients who took the anti-malarial drug. The World Health Organization also announced on Monday it had temporarily stopped running tests on the drug to review safety concerns. Fauci stopped short of saying the U.S. should follow France's lead, but told CNN it has become "more clear" that using hydroxychloroquine could lead to "adverse" cardiovascular effects.

An anonymous reader quotes a report from CNN: In new guidance for mathematical modelers and public health officials, the U.S. Centers for Disease Control and Prevention is estimating that about a third of coronavirus infections are asymptomatic. The CDC also says its "best estimate" is that 0.4% of people who show symptoms and have Covid-19 will die, and the agency estimates that 40% of coronavirus transmission is occurring before people feel sick.

The numbers are part of five planning scenarios that "are being used by mathematical modelers throughout the federal government," according to the CDC. Four of those scenarios represent "the lower and upper bounds of disease severity and viral transmissibility." The fifth scenario is the CDC's "current best estimate about viral transmission and disease severity in the United States." In that scenario, the agency described its estimate that 0.4% of people who feel sick with Covid-19 will die. For people age 65 and older, the CDC puts that number at 1.3%. For people 49 and under, the agency estimated that 0.05% of symptomatic people will die. The CDC cautions that these numbers are based on real data collected by the agency before April 29 and are subject to change. Still, the "current best estimate" number of 0.4% is significantly lower than the 3.4% mortality rate the World Health Organization warned in early March.

"As I see it, the 'best estimate' is extremely optimistic, and the 'worst case' scenario is fairly optimistic even as a best estimate. One certainly wants to consider worse scenarios," biologist Carl Bergstrom of the University of Washington told CNN. "By introducing these as the official parameter sets for modeling efforts, CDC is influencing the models produced by federal agencies, but also the broader scientific discourse because there will be some pressure to use the CDC standard parameter sets in modeling papers going forward," he said. "Given that these parameter sets underestimate fatality by a substantial margin compared to current scientific consensus, this is deeply problematic."

UPDATE (5/28): An epidemiologist at the Johns Hopkins Center for Health Security also contradict the CDC's low numbers, saying that after reviewing new widespread testing, "The current best estimates for the infection fatality risk are between 0.5% and 1%," according to NPR.

"But even a virus with a fatality rate less than 1% presents a formidable threat, Rivers says."

Further reading: Many Scientists Warn CDC's New Death Rate Estimates Far Too Low.

New submitter Way Smarter Than You shares a report from The Seattle Times: Humans aren't the only ones hankering for the days they could dine out at their cities' restaurants: Some rats that miss feasting on the scraps are becoming increasingly brazen to find new food sources, the Centers for Disease Control and Prevention warned Thursday. Amid stay-home restrictions set across the country to battle the spread of the novel coronavirus, many restaurants and cafes are closed or limited to takeout and delivery, and with the reduced sales, the restaurants' trash bins are no longer overflowing with scrumptious leftovers hoards of rodents subsisted on. Finding slimmer pickings than they used to, cities' critters are more aggressive, prompting CDC to issue guidance on how to deter them.

Since the start of the pandemic, there have been increased reports of rat cannibalism and infanticide in New York, as well as more rat complaints in residential areas -- including in Chicago -- as humans produce more food waste at home. Roving rat armies, including one caught on camera scavenging New Orleans' empty streets, are concerning to the CDC, which says rodents can carry disease. The CDC advises home and business owners to cover garbage cans, put bird and pet food out of reach and seal small holes rodents could access in buildings. If people follow established cleaning guidelines, they can avoid exposure to rodent-borne diseases, according to the agency.

An anonymous reader quotes a report from ZDNet: Some 66 million years ago, an asteroid hit the Earth on the eastern coast of modern Mexico, resulting in up to three quarters of plant and animal species living on the planet going extinct -- including the dinosaurs. Now, a team of researchers equipped with a supercomputer have managed to simulate the entire event, shedding light on the reasons that the impact led to a mass extinction of life. The simulations were carried out by scientists at Imperial College in London, using high performance computing (HPC) facilities provided by Hewlett Packard Enterprise. The research focused on establishing as precise an impact angle and trajectory as possible, which in turn can help determine precisely how the asteroid's hit affected the surrounding environment.

Various impact angles and speeds were considered, and 3D simulations for each were fed into the supercomputer. These simulations were then compared with the geophysical features that have been observed in the 110-mile wide Chicxulub crater, located in Mexico's Yucatan Peninsula, where the impact happened. The simulations that turned out to be the most consistent with the structure of the Chicxulub crater showed an impact angle of about 60 degrees. Such a strike had the strength of about ten billion Hiroshima bombs, and this particular angle meant that rocks and sediments were ejected almost symmetrically. This, in turn, caused a greater amount of climate-changing gases to be released, including billions of tonnes of sulphur that blocked the sun. The rest is history: firestorms, hurricanes, tsunamis and earthquakes rocked the planet, and most species disappeared from the surface of the Earth. The 60-degree angle constituted "the worse-case scenario for the lethality of the impact" because it maximized the ejection of rock and therefore, the production of gases, the scientists wrote.

"The researchers carried out almost 300 3D simulations before they were able to reach their conclusions, which was processed by the HPE Apollo 6000 Gen10 supercomputer located at the University of Leicester," adds ZDNet. "The 14,000-cores system, powered by Intel's Skylake chips, is supported by a 6TB server to accommodate large, in-memory calculations."

The mystery of why glass frogs have see-through skin has been solved, scientists say: the unusual feature is a type of camouflage. The Guardian reports: Glass frogs are found in tropical Central and South America, and get their name from their skin. However, the frogs are not truly transparent but translucent, with the skin on their backs typically a vivid green and their intestines and heart visible through their underbelly. This has led to a question that has kept scientists on the hop. "If predators cannot see straight though the frogs, why do glass frogs have transparent skin at all, and not the opaque camouflaged patterns of other tree frog species?" said Dr James Barnett, a postdoctoral researcher at McMaster University, Canada, who co-authored the study.

Barnett and colleagues say they have cracked the conundrum. "The frog is always green to generally match leaves, but leaves will differ in their brightness," said Barnett. The team say that while the color of the frog's body changes little against dark or light foliage, the legs are more translucent and hence shift in brightness, helping the amphibians to blend in. "By having translucent legs and resting with the legs surrounding the body, the frog's edge is transformed into a softer, less contrasting gradient from the leaf to the legs, and again from the legs to the body," said Barnett, noting that this makes the frog's outline less recognizable to predators. Writing in the U.S. journal Proceedings of the National Academy of Sciences, Barnett and colleagues report how they carried out three experiments.

Peter Piot, 71, one of the giants of Ebola and AIDS research, is still battling a coronavirus infection that hit him "like a bus" in March. From a report:"This is the revenge of the viruses," said Dr. Peter Piot, the director of the London School of Hygiene and Tropical Medicine. "I've made their lives difficult. Now they're trying to get me." Dr. Piot, 71 years old, is a legend in the battles against Ebola and AIDS. But Covid-19 almost killed him. "A week ago, I couldn't have done this interview," he said, speaking recently by Skype from his London dining room, a painting of calla lilies behind him. "I was still short of breath after 10 minutes." Looking back, ruefully, on being brought down by a virus after a life as a virus-hunter, Dr. Piot said he had misjudged his prey and had become the hunted.

"I underestimated this one -- how fast it would spread. My mistake was to think it was like SARS, which was pretty limited in scope. Or that it was like influenza. But it's neither." In 1976, as a graduate student in virology at the Institute of Tropical Medicine in Antwerp, Belgium, Dr. Piot was part of the international team that investigated a mysterious viral hemorrhagic fever in Yambuku, Zaire, now the Democratic Republic of Congo. To avoid stigmatizing the town, team members named the virus "Ebola" after a nearby river. Later, in the 1980s, he was one of the scientists who proved that the wasting disease known as "slim" in Africa was caused by the same virus that was killing young gay men elsewhere. From 1991 to 1994, he was president of the International AIDS Society, and then the first director of U.N.AIDS, the United Nations' anti-H.I.V. program.

An anonymous reader writes: There's an interesting analysis, which looks at several data points, to conclude that media may have flamed fears that drove the world to enforce lockdowns. From the story: "To put things in perspective, the virus is now known to have an infection fatality rate for most people under 65 that is no more dangerous than driving 13 to 101 miles per day. Even by conservative estimates, the odds of COVID-19 death are roughly in line with existing baseline odds of dying in any given year. Yet we put billions of young healthy people under house arrest, stopped cancer screenings, and sunk ourselves into the worst level of unemployment since the Great Depression. This from a virus that bears a survival rate of 99.99% if you are a healthy individual under 50 years old (1, 2).

"New York City reached over a 25% infection rate and yet 99.98% of all people in the city under 45 survived, making it comparable to death rates by normal accidents. But of course the whole linchpin of the lockdown argument is that it would have been even worse without such a step. Sweden never closed down borders, primary schools, restaurants, or businesses, and never mandated masks, yet 99.998% of all their people under 60 have survived and their hospitals were never overburdened. Why did we lock down the majority of the population who were never at significant risk? What will be the collateral damage? That is what this series will explore.

"In early February the World Health Organization said that travel bans were not necessary. On Feb. 17, just a month before the first U.S. lockdown, Dr. Anthony Fauci, the longtime director of the National Institute of Allergy and Infectious Diseases said that this new strain of coronavirus possessed "just minuscule" danger to the United States. In early March the U.S. surgeon general said that "masks are NOT effective in preventing [the] general public from catching coronavirus." As late as March 9, the day Italy started its lockdown, Dr. Fauci did not encourage cancellation of "large gatherings in a place [even if] you have community spread," calling it "a judgment call." NBA games were still being played. So how did we go from such a measured tone to locking up 97% of Americans in their homes seemingly overnight?" There's an argument to be made that lockdowns was perhaps the most responsible action a government could have enforced. Additionally, some Silicon Vally tech executives have argued that the media downplayed the significance of the coronavirus pandemic early on.

An anonymous reader shares a report: On Monday, Virgin Orbit attempted the first full flight of its orbital payload launch system, which includes a modified Boeing 747 called 'Cosmic Girl' that acts as a carrier aircraft for its air-launched rocket LauncherOne. While Virgin Orbit has flown Cosmic Girl and LauncherOne previously for different tests and demonstrations, this was the first end-to-end system test. Unfortunately, that test ended much earlier than planned -- just shortly after the LauncherOne rocket was released from Cosmic Girl. Cosmic Girl took off just before 12 PM PT (3 PM ET) from Mojave Air and Spaceport in California. The aircraft was piloted by Chief Test Pilot Kelly Latimer, along with her co-pilot Todd Ericson. The aircraft then flew to its target release point, where LauncherOne did manage a "clean release" from the carrier craft as planned at around 12:50 PM PT (3:50 PM ET), but Virgin noted just a few minutes later that the mission was subsequently "terminated."

An anonymous reader shares a report: The moon visits one of the spring constellations this week by traveling through the faint constellation of Virgo, the virgin. On 1 and 2 June, our natural satellite will pass close to Virgo's only bright star, Spica. Memorise its position and then return in the days to come to pick out the constellation's other, fainter stars. Spica is one of the 20 brightest stars in the night sky, located at a distance of about 250 light years. A blue giant star, containing around 10 times the Sun's mass, it is more than 20,000 times more luminous than our star.

NASA and SpaceX are closer than ever to a moment both have been preparing for since the beginning of the Commercial Crew program in 2010. SpaceX's Falcon 9 and Crew Dragon spacecraft are now set to fly with NASA astronauts Doug Hurley and Bob Behnken onboard, making a trip to the International Space Station, and both the agency and SpaceX announced today that they have officially passed the final flight readiness review, meaning everything is now a 'go' for launch. From a report: According to NASA Commercial Crew Program manager Kathy Leuders during a press conference on Monday, everything went well with all pre-launch flight checks thus far, including a full-length static test fire of the Falcon 9's engines, and a dress rehearsal of all launch preparation including strapping Hurley and Behnken into the rocket. The only remaining major hurdle for SpaceX and NASA now is the weather, which is currently only looking around 40% favorable for a launch attempt on schedule for Wednesday, May 27 at 4:33 PM EDT, though during today's press conference officials noted it is actually trending upwards as of today. SpaceX and NASA will be paying close attention to the weather between now and Wednesday, and since this is a highly sensitive mission with actual astronauts on board the spacecraft, you can bet that they'll err on the side of caution for scrubbing the launch if weather isn't looking good. That said, they do have a backup opportunity of May 30 in case they need to make use of that.

Prime minister Shinzo Abe has declared victory for the "Japan model" of fighting coronavirus as he lifted a nationwide state of emergency after seven weeks [Editor's note: the link may be paywalled; alternative source]. From a report: Speaking at a press conference on Monday evening in Tokyo, Mr Abe said that Japan had avoided an explosive increase in cases without the compulsory lockdowns used in Europe or the US. The ending of the state of emergency in the last five prefectures it covered -- Tokyo, Kanagawa, Saitama, Chiba and Hokkaido -- will mean that the world's fourth-largest economy can start to reopen for business. "In a characteristically Japanese way, we have all but brought this epidemic under control in the last month and a half," said Mr Abe. "Surely, it shows the power of the Japan model." Japan's constitution prohibits a compulsory lockdown but, under the state of emergency that began on April 7, the government requested voluntary social distancing and business closures. Under that regime, the number of new Covid-19 cases fell from 600-700 a day in mid-April to about 20-30 a day last week. The country has diagnosed 16,581 cases of coronavirus with 830 deaths -- many fewer than similar-sized populations in Europe or the US.