A previous post presented the fascinating history of the brick factory problem, which wonders about the smallest possible number of rail crossings when connecting kilns and storage yards, which is mathematically modeled by the crossing number of the complete bipartite graph . Proposed by Paul Turán after the Second World War, the first advances on […]
Humanities & Social Sciences • Science • Technology • Weekly Selection
19 elements to have atomic weights adjusted Aluminum, cadmium, gold and arsenic are among 19 elements that are having their atomic weights adjusted by the International Union of Pure and Applied Chemistry. More precise measurements are now available leading to the new weight calculations, which happens rarely. The atomic weight of nonmetal selenium hasn’t been […]
Magnetoception, the fantastic ability to perceive magnetic fields. A skill though impossible for long. It was difficult to assume that a 0.5 Gauss Earth’s magnetic field (your fridge has one with 100 Gauss) could have some effect on living things. However, the magnetic field perception was supported since the very beginning by experimental observation and […]
Symmetry is a major trait in the architecture of the vast majority of animals: if we exclude sponges, a typical animal body plan will show one or more planes of symmetry. Radial symmetry is considered the ancestral state for the Eumetazoa, with body plans such as the polyps and jellyfishes within the Cnidarians, usually with […]
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PET helps ID tau protein in the brain PET shows promise in detecting tau protein accumulation in the brain, according to a study in the journal Neuron. Researchers developed a chemical that binds with the substance and used PET to identify areas of the brain at risk of neuronal death. The approach was evaluated in […]
Last February I was giving a 101 Astronomy class early in the morning. It was Friday, the 15th. Just by chance, I was talking about the minor bodies of the Solar System when we started speaking about impacts on Earth. I showed some slides of the Tunguska event and how the devastated area was similar […]
Animals like spiders, snakes, scorpions, and cone snails inject venoms to their preys to immobilize or kill them. But what there is in these venoms that can trigger such a strong effect? The venom of these animals is actually a cocktail of toxins, from which one of the main components are peptides. Due to their […]
Humanities & Social Sciences • Science • Technology • Weekly Selection
Reprogrammed stem cells in mice could pave way to tissue regeneration Spanish scientists successfully forced mature cells into an embryonic-like state inside the bodies of living mice, creating so-called reprogrammed induced pluripotent stem cells. Transforming mature cells into stem-like cells “means turning back the clock when everything in the environment favors the opposite,” lead author […]
We saw at the end of the first entry of this series that, in spite of the adjective ‘true’ seeming to be semantically redundant in the sense of its role being equivalent to just assert exactly the same assertion to which it is applied, it is nevertheless grammatically non-redundant, in the sense that there are […]
The relevance of demand factors for explaining growth was stated almost simultaneously by Michal Kalecki and John Maynard Keynes in the 1930s. The main conclusion of the theory of effective demand is that spending determines income. Keynes stated that the marginal propensity to consume decreases when total income growths. Kalecki considered different propensities to consume […]