Daniel Lemire's blog

, 4 min read

Science and Technology links (May 22nd 2021)

  1. Most computer chips today in flagship phones and computers use a process based on a 5 nm or larger resolution. Finer resolutions usually translate into lower energy usage and lower heat production. Given that many of our systems are limited by heat or power, finer resolutions lead to higher performance. The large Taiwanese chip maker (TSMC) announced a breakthrough that might allow much finer resolutions (down to 1 nm). IBM recently reported a similar but less impressive breakthrough. It is unclear whether the American giant, Intel, is keeping up.
  2. Good science is reproducible. If other researchers follow whatever you describe in your research article, they should get the same results. That is, what you report should be an objective truth and not the side-effect of your beliefs or of plain luck. Unfornately, we rarely try to reproduce results. When we do, it is common to be unable to reproduce the results from a peer-reviewed research papers. The system is honor-based: we trust that people do their best to check their own results. What happens when mistakes happen? Over time, other researchers will find out. Unfortunately, reporting such failures is typically difficult. Nobody likes to make ennemies and the burden of the proof is always on you when you want to denounce other people’s research. It is so common that we have a name for the effect: the replication crisis. The reproduction crisis has attracted more and more attention because it is becoming an existential threat: if a system produces research that cannot be trusted, the whole institution might fall. We see the reproduction crisis in psychology, cancer research and machine learning. Researchers now report that unreproducible research can be cited 100 times more than reproducible research. It suggests that people who produce unreproducible research might have an advantage in their careers and that they might go up the ranks faster.
  3. Recent PCs and tablets store data on solid-state drives (SSDs) that can be remarkably fast. The latest Sony PlayStation has an SSD with a bandwidth exceeding 5 GB/s. Conventional (spinning) disks have lagged behind with a bandwidth of about 200 MB/s. However, conventional disks can be much larger. It seems, however, that conventional disks might be getting faster. The hard drive maker Seagate has been selling conventional disks that have a bandwidth of 500 MB/s.
  4. As you age, you accumulate cells that are dysfunctional and should otherwise die, they are called senescent cells. We are currently developing therapies to remove them. Martinez-Zamudio et al. report that a large fraction of some cells in the immune system of older human beings are senescent (e.g., 64%). Clearing these senescent cells could have a drastic effect. We shall soon know.
  5. There are 50 billion birds and 1.6 billion sparrows.
  6. Computer scientists train software neural networks (for artificial intelligence) using backpropagation. It seems that people believe that such a mechanism (backpropagation) is not likely to exist in biology. Furthermore, people seem to believe that in biological brain, learning is “local” (at the level of the synapse). Recently, researchers have shown that we can train software neural networks using another technique that is ‘biologically plausible’ called zero-divergence inference learning. The implicit assumption is that these software systems are thus a plausible model for biological brains. It is unclear to me whether that’s a valid scientific claim: is it falsifiable?
  7. Ancient Romans used lead for everything. It appears that Roman children suffered from lead poisoning and had a related high mortality rate.
  8. Knight et al. found strong evidence to support the hypothesis that vitamin D could help prevent breast cancer. Taking walks outside in the sun while not entirely covered provides your body with vitamin D.
  9. Mammal hearts do not regenerate very well. Hence, if your heart is damaged, it may never repair itself. It appears that some specific stem cells can survive when grafted to living hearts and induce regeneration.
  10. Persistent short sleep duration (6 hours or less) is associated with a 30% increased dementia risk. (Note that this finding does not imply that people sleeping a lot are in good health. It also does not imply that you are sick if you are sleeping little.)
  11. Researchers have rejuvenated the blood cells of old mice using a form of vitamin B3.
  12. There are 65 animal species that can laugh.
  13. Between the years 1300 and 1400, the area near Greenland became relatively free from ice, as it was effectively exporting its ice to subartic regions. It seems to match the beginning of the Little Ice Age, a time when, at least in Europe, cold temperatures prevailed.