The crossing number of a graph, defined as the minimum number of edge crossings arising when the graph is drawn in the plane, turns out to be a mathematical concept with a fascinating history. Lowell Beineke and Robin Wilson trace the origins of the crossing number, with particular emphasis in the war-time experiences of the […]
Humanities & Social Sciences • Science • Technology • Weekly Selection
Herbal remedy has cancerous side effect Aristolochia plants, which have been used in China for herbal remedies, have been found to cause cancer, according to two studies published in Science Translational Medicine. The plants contain a naturally carcinogenic compound called aristolochic acid, which causes more cell mutations than those caused by tobacco smoke and UV […]
TW Hydrae is a peculiar star. Although it is not bright enough to be visible to the unaided eye, it is relatively close to us, just 180 light-years away, and this makes it the closest T Tauri star in the sky. A T Tauri star is a solar system being born, they are still to […]
The locomotion of every moving system, alive or manufactured, is produced by the interaction between some movable components or appendages and the surrounding environment. This applies for every kind of surroundings: land, water or air. For water and air, Navier-Stokes equations allow predicting the interaction with the fluid with very high precision. In the case […]
Humanities & Social Sciences • Science • Technology • Weekly Selection
Varied smelling ability linked to genes Scientists at the New Zealand Institute for Plant and Food Research sequenced test subjects’ genomes to see if they could predict an individual’s smelling ability, and found clusters of genes that reliably predicted the person’s ability to smell four of 10 chemicals. “All of these genes are on different […]
This article is focused on a recent paper [PDF] written by Jo Day from the Department of Classics of the University College Dublin exploring the links between botany and archaeology using case studies from ancient Mediterranean civilizations. Archaeology is more associated with the discovery of tombs and ancient human remains than with plants. However, the […]
No one denies that there exist some forms of discrimination in the labor market and in many other places of our societies. There is, however, debate about the cause or causes of this discrimination and about the best ways to deal with it. Does discrimination start with some sort of education or social pressure that […]
Humanities & Social Sciences • Science • Technology • Weekly Selection
Methane released from Arctic permafrost could cost trillions worldwide Scientists warn that large amounts of methane that could be released from the melting Arctic permafrost could have a huge global economic impact. The release of 50-gigatonnes of methane over 10 years could cost $60 trillion worldwide, according to a study published in the journal Nature […]
There is a strong tendency to consider that every scientific or technical solution to a particular problem is irrefutable. Nowadays, scientific and technological knowledge usually eludes public criticism and even we have seen how important government decision making were made by the so-called technocrats . We often forget the contingency of this knowledge, the fact […]
Choose your favorite convex polyhedron in the space. Make sure it is convex, since the current post is restricted to that kind of polyhedra An unfolding of your convex polyhedron is a development of its surface to a single polygon in the plane (possibly overla pping). In order to obtain an unfolding, the surface of […]