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Comment Re:.3um (Score 2) 391

by MacAndrew (#63966690) Attached to: Are Face Masks Effective? CBS News Explains What We Know

I agree smaller dose intuitively means less of a hazard of an infection putting down roots before the immune system wipes it out. However, I've never seen data for this.

IIRC coronavirus particles were around 0.1 um, but the virus would fall apart traveling bare. N95 do filter in that range in any event, just not at the advertised and tested level of an N95's 95% @ 0.3 um (you can get N100s which don't quite hit 100%; it's a rounding thing). Aerosols are typically much larger, 1+ um up, then transition to visible droplets around 20-100 um.

Comment Re: never underestimate stupidity (Score 2) 391

by MacAndrew (#63966624) Attached to: Are Face Masks Effective? CBS News Explains What We Know

I'm afraid another pivotal concern may have been costs: inferior masks such as surgical are much cheaper. So, here in Virginia the hospital admin logic went, the mask they chose should be the standard for all purposes (our hospital required visitors to give up their personal N95s for a surgical mask, which was at least free).

As even more damning evidence of institutional thinking, the same hospital network required my PCP to wear a mask for telemedicine visits. I burst out laughing when I saw him and asked, "I don't mean to be rude, but are y'all familiar with the germ theory of disease?" He apologized and said the rule simply was that all patient-facing meeting required a mask. So there, standards.

Submission + - From rocks to icebergs, the natural world tends to break into cubes (sciencemag.org)

Submitted by sciencehabit
sciencehabit writes: Perhaps the Cubists were right. Researchers have found that when everything from icebergs to rocks breaks apart, their pieces tend to resemble cubes. The finding suggests a universal rule of fragmentation at scales ranging from the microscopic to the planetary.

The scientists started their study “fragmenting” an abstract cube in a computer simulation by slicing it with 50 two-dimensional planes inserted at random angles. The planes cut the cube into 600,000 fragments, which were, on average, cubic themselves—meaning that, on average, the fragments had six sides that were quadrangles, although any individual fragment need not be a cube. The result led the researchers to suspect that cubes might be a common feature of fragmentation.

The researchers tried to confirm this hunch using real-world measurements. They headed to an outcrop of the mineral dolomite on the mountain Hármashatárhegy in Budapest, Hungary, and counted the number of vertices in cracks in the stone face. Most of these cracks formed squarish shapes, which is one of the faces of a cube, regardless of if they had been weathered naturally or had been created by humans dynamiting the mountain.

Finally, the team created more-powerful supercomputer simulations modeling the breakup of 3D materials under idealized conditions—like a rock being pulled equally in all directions. Such cases formed polyhedral pieces that were, in an average sense, cubes..
Medicine

Can You Get Covid-19 Again? It's Very Unlikely, Experts Say 55

Posted by msmash from the closer-look dept.
An anonymous reader shares a report: The anecdotes are alarming. A woman in Los Angeles seemed to recover from Covid-19, but weeks later took a turn for the worse and tested positive again. A New Jersey doctor claimed several patients healed from one bout only to become reinfected with the coronavirus. And another doctor said a second round of illness was a reality for some people, and was much more severe. These recent accounts tap into people's deepest anxieties that they are destined to succumb to Covid-19 over and over, feeling progressively sicker, and will never emerge from this nightmarish pandemic. And these stories fuel fears that we won't be able to reach herd immunity -- the ultimate destination where the virus can no longer find enough victims to pose a deadly threat.

But the anecdotes are just that -- stories without evidence of reinfections, according to nearly a dozen experts who study viruses. "I haven't heard of a case where it's been truly unambiguously demonstrated," said Marc Lipsitch, an epidemiologist at the Harvard T.H. Chan School of Public Health. Other experts were even more reassuring. While little is definitively known about the coronavirus, just seven months into the pandemic, the new virus is behaving like most others, they said, lending credence to the belief that herd immunity can be achieved with a vaccine. It may be possible for the coronavirus to strike the same person twice, but it's highly unlikely that it would do so in such a short window or to make people sicker the second time, they said. What's more likely is that some people have a drawn-out course of infection, with the virus taking a slow toll weeks to months after their initial exposure. People infected with the coronavirus typically produce immune molecules called antibodies. Several teams have recently reported that the levels of these antibodies decline in two to three months, causing some consternation. But a drop in antibodies is perfectly normal after an acute infection subsides, said Dr. Michael Mina, an immunologist at Harvard University.

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