There is a theory in criminology that says that if a broken window in a building is left unrepaired, that building will soon have all its other windows broken. The rationale behind it is that signs of urban disorder and untended public spaces elicit antisocial behaviour. The idea is reminiscent of the concept of “criticality” […]
Economics • Mathematics • Medicine • Pharmacy
Blood from donations is separated into three components: red cells, platelets and plasma, and one component or another is then transfused into patients according to their needs. The conditions for storage differ for each component: red cell concentrates can be kept for up to 42 days at temperatures of 1-6ºC. Platelet concentrates (PC) are stored […]
What is chaos? Chaos is a concept related to dynamical systems, that are nothing but systems than can be described by amounts that change in time. There are examples of dynamical systems everywhere: the amount of money in your bank account, your weight, your room’s temperature, … all of them evolve in time, and therefore […]
This post is dedicated to the memory of Professor Ferran Hurtado , inspirational friend and colleague. Triangulations are extremely useful in computer graphics, with terrain modeling being an outstanding example: A mesh of points in 2D is triangulated and then the triangulation is lifted to obtain an -monotone polyhedral surface in 3D, called a 2.5D […]
Triangles are, definitely, among the most used mathematical objects. One of the reasons is that they are simple (actually the smallest polygon). Another very important reason is that they are rigid, which is the property behind the many structures composed by triangles we can see in our daily life. But, surprisingly enough, triangulations are not […]
The field of population dynamics lies between mathematics and biology. Its subject of study is the evolution of biological populations with time. The natural language for dynamical problems is that of differential equations, and population dynamics is not an exception to this rule. Such a powerful tool was well known since the times of Isaac […]
We all know how Spider-Man moves through the city, shooting spider-webs from wall to wall. But, have you ever wondered if he is actually using the shortest route? And, if so, how does he compute it? Since walls introduce a third dimension into the problem, the algorithms in a usual GPS navigator are no longer […]
An old problem, restated by Martin Gardner in 1959, asked if six cigarettes that can be placed so that each touches the other. Gardner was surprised by fifteen readers discovering that actually seven cigarettes can be arranged with that condition . Some years later, in 1968, Littlewood raised the question if it possible in 3-space […]
When was the last time you used a postage stamp? Even if it was a long time ago, you may have hold in your hands a strip of stamps. Maybe you have even tried to fold it into a stack, one stamp wide, so that the strip was easier to store. Have you ever wondered […]
You play rock-paper-scissors against someone. What is the best strategy? Of course, it depends of what your opponent does. If he is someone who always plays “rock”, then you better play “paper”. But if your opponent is not that naïve and searches for his best play, what would you do? The first thing to notice […]