"It might be the next best thing to a coronavirus vaccine," writes the Los Angeles Times. "Scientists have devised a way to use the antibody-rich blood plasma of Covid-19 survivors for an upper-arm injection that they say could inoculate people against the virus for months." Using technology that's been proven effective in preventing other diseases such as hepatitis A, the injections would be administered to high-risk health care workers, nursing home patients, or even at public drive-through sites — potentially protecting millions of lives, the doctors and other experts say. The two scientists who spearheaded the proposal — an 83-year-old shingles researcher and his counterpart, an HIV gene therapy expert — have garnered widespread support from leading blood and immunology specialists, including those at the center of the nation's Covid-19 plasma research.

But the idea exists only on paper. Federal officials have twice rejected requests to discuss the proposal, and pharmaceutical companies — even acknowledging the likely efficacy of the plan — have declined to design or manufacture the shots, according to a Los Angeles Times investigation... There is little disagreement that the idea holds promise; the dispute is over the timing. Federal health officials and industry groups say the development of plasma-based therapies should focus on treating people who are already sick, not on preventing infections in those who are still healthy...

But scientists who question the delay argue that the immunity shots are easy to scale up and should enter clinical trials immediately. They say that until there's a vaccine, the shots offer the only plausible method for preventing potentially millions of infections at a critical moment in the pandemic. "Beyond being a lost opportunity, this is a real head-scratcher," said Dr. Michael Joyner, a Mayo Clinic researcher who leads a program sponsored by the Food and Drug Administration to capitalize on coronavirus antibodies from COVID-19 survivors. "It seems obvious." The use of so-called convalescent plasma has already become widespread. More than 28,000 patients have already received the IV treatment, and preliminary data suggest that the method is safe.

"A newly-discovered comet is giving skywatchers quite the show during the month of July," reports CBS News: Astronomers discovered the comet, known as Comet C2020 F3 NEOWISE, back in March. It was named for the NASA mission that spotted it, for the Near-Earth Object Wide-field Infrared Survey Explorer... But astronomers knew they found something unique when they spotted Neowise. On July 3, Neowise was closer to the sun than the orbit of Mercury, coming dangerously close to breaking apart. The sun heated up much of the comet's icy makeup, erupting in a large debris trail of gas and dust.

Measuring about 3 miles across, Neowise is considered a fairly large comet — providing skywatchers with a spectacular view from Earth. The comet, which has a bright opulent tail, has been putting on a stunning show in the early hours before sunrise in the Northern Hemisphere... But late sleepers need not worry — the comet will start appearing in the evening, just after sunset, starting Saturday.

To view it, people in the Northern Hemisphere can look to the northwestern sky, just below Ursa Major, commonly known as the Big Dipper constellation. Scientists say the comet will be visible across the Northern Hemisphere for about another month.
The comet is made up of material dating back 4.6 billion years, to the origins of our solar system, according to the article. "The event is truly a once-in-a-lifetime experience — the comet takes about 6,800 years to complete its path around the sun, according to NASA..."

"NASA says it will be one of the brightest comets this century."

An anonymous reader quotes Forbes: Conventional theory has it that Planet 9 — our outer solar system's hypothetical 9th planet — is merely a heretofore undetected planet, likely captured by our solar system at some point over its 4.6 billion year history. But Harvard University astronomers now raise the possibility that orbital evidence for Planet 9 could possibly be the result of a missing link in the decades-long puzzle of dark matter. That is, a hypothetical primordial black hole with a horizon size no larger than a grapefruit, and with a mass 5 to 10 times that of Earth.

In a paper accepted for publication in The Astrophysical Journal Letters, the co-authors argue that observed clustering of extreme trans-Neptunian objects suggest some sort of massive super-earth type body lying on the outer fringes of our solar system. Perhaps as much as 800 astronomical units (Earth-Sun distances) out...

If they exist, such primordial black holes would require new physics and go a long way towards solving the mystery of the universe's missing mass, or dark matter.
Their argument also constitutes a "new method to search for black holes in the outer solar system based on flares that result from the disruption of intercepted comets," according to a statement from the Harvard-Smithsonian Center for Astrophysics. The paper was co-authored by Avi Loeb, chair of Harvard's astronomy department, who points out that "Because black holes are intrinsically dark, the radiation that matter emits on its way to the mouth of the black hole is our only way to illuminate this dark environment."

And in an explanatory video, Mike Brown, a planetary astronomy professor at CalTech, suggests another way it could be significant. "All those people who are mad that Pluto is no longer a planet can be thrilled to know that there is a real planet out there still to be found."

Research continues in a field which involves using the spin and magnetism of electrons in solid-state devices — spintronics.

hackingbear shared this report from Nature: Electric control of magnetic vortex dynamics in a reproducible way on an ultrafast time scale is a key element in the quest for efficient spintronic devices with low-energy consumption. Researchers in China and Germany demonstrated a simple method for controlling magnetic patterns that are useful for data storage and information processing.

Magnetic nanostructures are engineered as to host swirling magnetic vortices. The vortex intrinsic properties such as the vortex sense of rotations or polarity are well defined and thus are predestinate as digital information carriers. Furthermore, the magnetic nanostructures are readily integrated in existing computers. Chenglong Jia from Lanzhou University, Jamal Berakdar from Martin-Luther Universitat Halle-Wittenberg and their co-workers demonstrated how to process the so stored information swiftly by switching both the vortex's sense of rotation and the orientation of its magnetic field using at a simple sequence of ultra-short, low average-energy electric-field pulses. The team believe that their method is scalable, non-invasive, reliable and reversible, fullfing thus important prerequisites for practical implementation.

A new Motherboard article interviews William, a ventilator refurbisher who's repaired at least 70 broken ventilators that he's bought on eBay and from other secondhand websites, then sold to U.S. hospitals and governments to help handle a spike in COVID-19 patients.

He's part of a grey-market supply chain that's "essentially identical to one used by farmers to repair John Deere tractors without the company's authorization and has emerged because of the same need to fix a device without a manufacturer's permission..." The issue is that, like so many other electronics, medical equipment, including ventilators, increasingly has software that prevents "unauthorized" people from repairing or refurbishing broken devices, and Medtronic will not help him fix them... Faced with a global pandemic, hospitals, biomedical technicians, right to repair activists, and refurbishers like William say that medical device manufacturers are profiteering by putting up artificial barriers to repair that drive up the cost of medical care in the United States and puts patient lives in danger. They describe difficulty getting parts and software, delays in getting service from "authorized" technicians, and a general sense of frustration as few manufacturers appear ready to loosen their repair restrictions during the COVID-19 crisis.

For the past decade, medical device manufacturers have refused to sell replacement parts and software to hospitals and repair professionals unless they pay thousands of dollars annually to become "authorized" to work on machines. The medical device industry has lobbied against legislation that would make it easier to repair their machines, refused to release repair manuals, and used copyright law to threaten those who have made repair manuals available to the public. The technicians who are unable to gain access to repair parts, manuals, and software are not random people who are deciding on a whim to try to fix complex medical equipment that is going to be used on sick patients. Hospitals and trained professionals are regularly unable to fix the equipment that they own unless they pay for expensive service contracts or annual trainings from manufacturers.

While hospitals deal with a resurgent coronavirus that is overtaxing intensive care units across the country, their biomedical technicians are wasting time on the phone and in Kafkaesque email exchanges with medical device manufacturers, pleading for spare parts, passwords to unlock diagnostic modes, or ventilator repair manuals.
The article notes that newer medical devices even have "more advanced anti-repair technologies built into them. Newer ventilators connect to proprietary servers owned by manufacturers to verify that the person accessing it is authorized by the company to do so."

Slashdot reader shirappu writes: AI|Writer is an experiment in which artificial intelligence is used to simulate both real and fictitious famous personalities through written correspondence. Users can ask questions and receive explanations from simulated versions of Isaac Newton, Alfred Hitchcock, Marie Curie, Mary Shelley, and many more.
The Next Web calls it "a new experiment by magician and novelist Andrew Mayne," pointing out that it's using OpenAI's new text generator API. Other simulated conversations include Ada Lovelace, Alan Turing, Stephen Hawking, Richard Feynman, Isaac Asimov, Benjamin Franklin, and even Edgar Allen Poe.

"We have all kinds of theoretical ideas about AI and what counts as real or not," Mayne said on Twitter, "however I think you just have to be pragmatic and just ask: What can it do? I think this gets lost in a lot of discussions about AI. The end goal isn't a witty chatbot. It's to expand our knowledge."

There's a wait list for access to the site "so we can make sure everything works right and we don't accidentally create Skynet," Mayne jokes on Twitter. But assuming this isn't another magic trick, The Next Web is already reporting on some of the early results: The system first works out the purpose of the message and the intended recipient by searching for patterns in the text. It then uses the API's internal knowledge of that person to guess how they would respond in their written voice. The digitized characters can answer questions about their work, explain scientific theories, or offer their opinions. For example, Marie Curie gave a lesson on radiation, H.G. Wells revealed his inspiration for The Time Machine, while Alfred Hitchcock compared Christopher Nolan's Interstellar to Stanley Kubrick's 2001...

The characters could also compare their own eras with the present day... Mayne says the characters did well with historical facts, but could be "quite erratic with matters of opinion" and "rarely reply to the same question in the same way." He demonstrated these variations by asking both Newton and Gottfried Leibniz who invented calculus. "Newton almost always insists that he invented Calculus alone and is pretty brusque about it," Mayne wrote on his website. "Leibniz sometimes says he did. Other times he'll be vague." At one point, Leibniz even threatened to kill Mayne if he tried to take the credit for the discovery.

As well as historical figures, the system can respond in the voice of fictional characters. In fact, Mayne says the most "touching" message he's received was this reply from the Incredible Hulk.
Another conversation shows Bruce Wayne's response when asked to make a donation to support freeing the Joker...

Rick Schumann writes: Researchers at a Cleveland clinic performed a study with 1,914 patients into a phenomenon called "Broken Heart Syndrome," where someone can be experiencing heart attack-like symptoms, but it's not a heart attack or anything related to blocked blood flow to the heart. Turns out that it seems likely that the aggregate stresses of the pandemic (so-called "social distancing," lack of contact with fellow humans, enforced isolation, and so on) appear to create emotional stresses that manifest with physical symptoms that mimic a heart attack.

"The pandemic has created a parallel environment which is not healthy," said Dr. Ankur Kalra, the cardiologist who led the study. "Emotional distancing is not healthy. The economic impact is not healthy. We've seen that as an increase in non-coronavirus deaths, and our study says that stress cardiomyopathy has gone up because of the stress that the pandemic has created." The study didn't examine whether or not there could be a medical link between this phenomenon and the coronavirus, but all the participants in the study were tested for infection and were found to be free of the virus. The study has been published in the journal JAMA Network Open.

Long-time Slashdot reader kartis writes: Canada's Supreme Court upheld the Genetic Non-Discrimination Act (GINA) which prohibits under criminal penalty, employers or insurers from demanding or using genetic information. This was a result of a private member's bill in Parliament, which meant it passed without the government's support, and in fact both the Federal government and Quebec government (which had gotten it declared unconstitutional as outside federal powers) argued that it extended criminal powers into a provincial jurisdiction. Well, the Supreme Court has surprisingly upheld it in a 5-4 decision, which means great things for Canadians' privacy, and also suggests a wider ability for federal privacy legislation than many jurists had thought.

A peculiar bacterial enzyme has allowed researchers to achieve what even the popular CRISPR-Cas9 genome-editing system couldn't manage: targeted changes to the genomes of mitochondria, cells' crucial energy-producing structures. From a report: The technique -- which builds on a super-precise version of gene editing called base editing -- could allow researchers to develop new ways to study, and perhaps even treat, diseases caused by mutations in the mitochondrial genome. Such disorders are most often passed down maternally, and impair the cell's ability to generate energy. Although there are only a small number of genes in the mitochondrial genome compared with the nuclear genome, these mutations can particularly harm the nervous system and muscles, including the heart, and can be fatal to people who inherit them.

But it has been difficult to study such disorders, because scientists lacked a way to make animal models with the same changes to the mitochondrial genome. The latest technique marks the first time that researchers have made such targeted changes, and could allow researchers to do this. "It's a very exciting development," says Carlos Moraes, a mitochondrial geneticist at the University of Miami in Florida. "The ability to modify mitochondrial DNA would allow us to ask questions that, before, we could not." The work was published on 8 July in Nature.

Can a daily drink or two lead to better health? For many years, the federal government's influential dietary guidelines implied as much, saying there was evidence that moderate drinking could lower the risk of heart disease and reduce mortality. But now a committee of scientists that is helping to update the latest edition of the Dietary Guidelines for Americans is taking a harder stance on alcohol. From a report: The committee said in a recent conference call that it plans to recommend that men and women who drink limit themselves to a single serving of wine, beer or liquor per day. Do not drink because you think it will make you healthier, the committee says: It won't. And it maintains that drinking less is generally better for health than drinking more. That message is a departure from previous guidelines, which since 1980 have defined "moderate" drinking as up to two drinks a day for men and one for women. Government agencies have also long defined a standard drink as 12 ounces of regular beer, five ounces of wine, or one and a half ounces of distilled spirits (40 percent alcohol), amounts often exceeded in Americans' typical "drink."

Between 1990 and 2010, many editions of the guidelines, which are updated every five years, discouraged heavy drinking and warned pregnant women and people with certain medical conditions not to drink. But they also noted that moderate drinking was linked to fewer heart attacks and lower mortality. The 2010 guidelines mentioned that moderate drinking may even "help to keep cognitive function intact with age." The new recommendation would be a victory for experts who have long questioned the health halo around moderate drinking. They say that studies showing it can protect health are deeply flawed, and that any potential cardiovascular benefits would be outweighed by the fact that alcohol is a leading preventable cause of cancer. According to the National Cancer Institute, even one drink a day increases the risk of breast, esophageal and oral cancer. The new advice is not yet final. The advisory panel is expected to include it in a report that it will release publicly in mid-July and submit to the Department of Agriculture and the Department of Health and Human Services. Those two agencies are scheduled to publish the official dietary guidelines later this year.

Special cells in giant clams shift the wavelength of light to protect them from UV radiation and increase the photosynthetic activity of their symbionts, shows research from King Abdullah University of Science and Technology -- originally intended as a photonics investigation. Phys.Org reports: Like corals, giant clams are important players in reef ecosystems and live in symbiosis with photosynthetic Symbiodiniaceae algae. The clams also have special cells, known as iridocytes, that can manipulate light via layers of nanoreflectors within each cell. Earlier work has shown that these iridocytes scatter and reflect light to increase the photosynthetic efficiency of the Symbiodiniaceae algae. Now, a team of researchers at the Red Sea Research Center and the Photonics Laboratory have discovered another way that iridocytes help the symbiont to photosynthesize. The researchers studied the morphology and optical characteristics of iridocytes in the giant clam Tridacna maxima and found that they absorb UV radiation and re-emit it as longer wavelength, photosynthetically useful light.

Ram Chandra Subedi, one of the study's authors, explains that the iridocytes contain alternating layers of high-refractive index guanine crystal and lower refractive index cytoplasm. Compressing and relaxing these layers enables the cell to tune its effect on light. As a result, "the guanine palettes not only reflect harmful UV radiation but also absorb it, and emit light at higher wavelengths which are safe and useful for photosynthesis," he explains. This increases the amount of photosynthetically active radiation available to the algal symbiont and also helps protect both the clams and algae from UV radiation. This photoprotective effect enables giant calms to live in very shallow tropical waters where there is enough light for photosynthesis, but also potentially harmful UV radiation levels. The report adds that this research may help explain the mantle colors of giant clams. "The idea is that the vibrant colors of giant clams are not due to optical differences in the tissue, but rather differences in the distribution or abundance of symbionts relative to iridocytes in each individual," reports Phys.Org.

The research has been published in the journal Frontiers in Marine Science.

Trying to get an up close and personal look at the solar system's gas giants is a tricky and dangerous journey. From a report: Jupiter, like the other gas giants, doesn't have a rocky surface, but that doesn't mean it's just a massive cloud floating through the vacuum of space. It's made up of mostly helium and hydrogen, and as you move from the outer layers of the atmosphere toward the deeper parts, that gas grows denser and the pressures become more extreme. Temperatures quickly rise. In 1995, NASA's Galileo mission sent a probe into Jupiter's atmosphere; it broke up at about 75 miles in depth. Pressures here are over 100 times more intense than anything on Earth. At the innermost layers of Jupiter that are 13,000 miles deep, the pressure is 2 million times stronger than what's experienced at sea level on Earth, and temperatures are hotter than the sun's surface.

So clearly, no human is going to be able to venture too far down into Jupiter's depths. But would it be safe to simply orbit the planet? Perhaps we could establish an orbital space station, right? Well, there's another big problem when it comes to Jupiter: radiation. The biggest planet in the solar system also boasts its most powerful magnetosphere. These magnetic fields charge up particles in the vicinity, accelerating them to extreme speeds that can fry a spacecraft's electronics in moments. Spaceflight engineers have to figure out an orbit and spacecraft design that will reduce the exposure to this radiation. NASA figured this out with the triple-arrayed, perpetually spinning Juno spacecraft, but it doesn't look as if this would be a feasible design for a human spacecraft. Instead, for a crewed spacecraft to safely orbit or fly past Jupiter, it would have to keep a pretty significant distance away from the planet.

An anonymous reader quotes a report from Phys.Org: A ringing bell vibrates simultaneously at a low-pitched fundamental tone and at many higher-pitched overtones, producing a pleasant musical sound. A recent study, just published in the Journal of the Atmospheric Sciences by scientists at Kyoto University and the University of Hawai'i at Mnoa, shows that the Earth's entire atmosphere vibrates in an analogous manner, in a striking confirmation of theories developed by physicists over the last two centuries. In the case of the atmosphere, the "music" comes not as a sound we could hear, but in the form of large-scale waves of atmospheric pressure spanning the globe and traveling around the equator, some moving east-to-west and others west-to-east. Each of these waves is a resonant vibration of the global atmosphere, analogous to one of the resonant pitches of a bell.

Now in a new study by Takatoshi Sakazaki, an assistant professor at the Kyoto University Graduate School of Science, and Kevin Hamilton, an Emeritus Professor in the Department of Atmospheric Sciences and the International Pacific Research Center at the University of Hawaii at Mnoa, the authors present a detailed analysis of observed atmospheric pressure over the globe every hour for 38 years. The results clearly revealed the presence of dozens of the predicted wave modes. The study focused particularly on waves with periods between 2 hours and 33 hours which travel horizontally through the atmosphere, moving around the globe at great speeds (exceeding 700 miles per hour). This sets up a characteristic "chequerboard" pattern of high and low pressure associated with these waves as they propagate. "For these rapidly moving wave modes, our observed frequencies and global patterns match those theoretically predicted very well," stated lead author Sakazaki. "It is exciting to see the vision of Laplace and other pioneering physicists so completely validated after two centuries."

Spreading rock dust on farmland could suck billions of tons of carbon dioxide from the air every year, according to the first detailed global analysis of the technique. The Guardian reports: The chemical reactions that degrade the rock particles lock the greenhouse gas into carbonates within months, and some scientists say this approach may be the best near-term way of removing CO2 from the atmosphere. The rock dust approach, called enhanced rock weathering (ERW), has several advantages, the researchers say. First, many farmers already add limestone dust to soils to reduce acidification, and adding other rock dust improves fertility and crop yields, meaning application could be routine and desirable.

Basalt is the best rock for capturing CO2, and many mines already produce dust as a byproduct, so stockpiles already exist. The researchers also found that the world's biggest polluters, China, the U.S. and India, have the greatest potential for ERW, as they have large areas of cropland and relatively warm weather, which speeds up the chemical reactions. The analysis, published in the journal Nature, estimates that treating about half of farmland could capture 2 billion tons of CO2 each year, equivalent to the combined emissions of Germany and Japan. The cost depends on local labor rates and varies from $80 per ton in India to $160 in the U.S., and is in line with the $100-150 carbon price forecast by the World Bank for 2050, the date by which emissions must reach net zero to avoid catastrophic climate breakdown.

An anonymous reader quotes a report from Phys.Org: Tiny, 3-D printed cubes of plastic, with intricate fractal voids built into them, have proven to be effective at dissipating shockwaves, potentially leading to new types of lightweight armor and structural materials effective against explosions and impacts. "The goal of the work is to manipulate the wave interactions resulting from a shockwave," said Dana Dattelbaum, a scientist at Los Alamos National Laboratory and lead author on a paper to appear in the journal AIP Advances. "The guiding principles for how to do so have not been well defined, certainly less so compared to mechanical deformation of additively manufactured materials. We're defining those principles, due to advanced, mesoscale manufacturing and design."

The researchers tested their fractal structures by firing an impactor into them at approximately 670 miles per hour. The structured cubes dissipated the shocks five times better than solid cubes of the same material. Although effective, it's not clear that the fractal structure is the best shock-dissipating design. The researchers are investigating other void- or interface-based patterns in search of ideal structures to dissipate shocks. New optimization algorithms will guide their work to structures outside of those that consist of regular, repeating structures. Potential applications might include structural supports and protective layers for vehicles, helmets, or other human-wearable protection. The research will be published in the July 2020 issue of AIP Advances.

Doctors may be missing signs of serious and potentially fatal brain disorders triggered by coronavirus, as they emerge in mildly affected or recovering patients, scientists have warned. From a report: Neurologists are on Wednesday publishing details of more than 40 UK Covid-19 patients whose complications ranged from brain inflammation and delirium to nerve damage and stroke. In some cases, the neurological problem was the patient's first and main symptom. The cases, published in the journal Brain, revealed a rise in a life-threatening condition called acute disseminated encephalomyelitis (Adem), as the first wave of infections swept through Britain. At UCL's Institute of Neurology, Adem cases rose from one a month before the pandemic to two or three per week in April and May. One woman, who was 59, died of the complication. A dozen patients had inflammation of the central nervous system, 10 had brain disease with delirium or psychosis, eight had strokes and a further eight had peripheral nerve problems, mostly diagnosed as Guillain-Barre syndrome, an immune reaction that attacks the nerves and causes paralysis. It is fatal in 5% of cases.

After hundreds of experts urged the World Health Organization to review mounting scientific research, the agency acknowledged on Tuesday that airborne transmission of the coronavirus may be a threat in indoor spaces. The New York Times reports: W.H.O. expert committees are going over evidence on transmission of the virus and plan to release updated recommendations in a few days, agency scientists said in a news briefing. The possibility of airborne transmission, especially in "crowded, closed, poorly ventilated settings, cannot be ruled out," said Dr. Benedetta Allegranzi, who leads the W.H.O.'s committee on infection prevention and control. She said the agency recommends "appropriate and optimal ventilation" of indoor environments, as well as physical distancing.

Agency staff fielded several questions from reporters about transmission of the virus by air, prompted by an open letter from 239 experts calling on the agency to review its guidance. Many of the letter's signatories have collaborated with the W.H.O. and served on its committees. [...] W.H.O. scientists said that for the past few months, the infection prevention committee has been weighing the evidence on all the ways in which the coronavirus spreads, including by tiny droplets or aerosols. "We acknowledge that there is emerging evidence in this field, as in all other fields," Dr. Allegranzi said. "And therefore, we believe that we have to be open to this evidence and understand its implications regarding the modes of transmission and also regarding the precautions that need to be taken." It will also be important to understand the importance of transmission by aerosols compared with larger droplets, and the dose of the virus needed for infection from aerosols, she said. "These are fields that are really growing and for which there is evidence emerging, but it is not definitive," she said. "However, the evidence needs to be gathered and interpreted, and we continue to support this."

The American Mathematical Society has announced the passing of Ronald Graham, "one of the principal architects of the rapid development worldwide of discrete mathematics in recent years." He died July 6th at the age of 84. From the report: Graham published more than 350 papers and books with many collaborators, including more than 90 with his wife, Fan Chung, and more than 30 with Paul Erdos. In addition to writing articles with Paul Erdos, Graham had a room in his house reserved for Erdos's frequent visits, he administered the cash prizes that Erdos created for various problems, and he created the Erdos number, which is the collaboration distance between a mathematician and Erdo's. He also created Graham's number in a 1971 paper on Ramsey theory written with Bruce Rothschild, which was for a time the largest number used in a proof.

Graham received his PhD from the University of California, Berkeley in 1962 under the direction of D.H. Lehmer. He worked at Bell Laboratories until 1999, starting as director of information sciences and ending his tenure there as chief scientist. Graham then joined the faculty at the University of California, San Diego and later became chief scientist at the California Institute for Telecommunications and Information Technology, a joint operation between the university and the University of California, Irvine. [...] Graham was an AMS member since 1961. For more information, see his "special page," these video interviews by the Simons Foundation, an audio interview about the mathematics of juggling, and his page at the MacTutor website. Graham's most recent appearance on Slashdot was in 2016, when a trio of researchers used a supercomputer to generate the largest math proof ever at 200 terabytes in size. The math problem was named the boolean Pythagorean Triples problem and was first proposed back in the 1980's by mathematician Ronald Graham.

Some days seem to pass very slowly while some weeks, and even months, fly by. A set of simple perception tests illustrate some factors that can distort our sense of time.

Brazilian President Jair Bolsonaro has tested positive for Covid-19, following months of downplaying the virus. From a report: Bolsonaro himself announced the result, speaking on Brazilian TV channels Tuesday. "Everyone knew that it would reach a considerable part of the population sooner or later. It was positive for me," he said, referring to the Covid-19 test he took Monday. "On Sunday, I wasn't feeling very well. On Monday, it got worse when I started feeling tired and some muscle pain. I also had a 38-degree [Celsius] fever. Given those symptoms, the presidential doctor said there was suspicion of Covid-19," Bolsonaro said, adding that he then went to hospital where scans of his lungs "came back clean."

Earlier on Tuesday, Bolsonaro told CNN affiliate CNN Brasil that he had been treated with hydroxychloroquine and azithromycin as he awaited the result of his fourth Covid-19 test in four months. Hydroxychloroquine, though enthusiastically boosted by both Bolsonaro and US President Donald Trump, has not been proven as an effective treatment for Covid-19. Bolsonaro nevertheless credited the controversial antimalarial drug for his well-being on Tuesday. "I am feeling very well. I believe that the way they administered the hydroxychloroquine on, the effect was immediate," he said.