4-D printing remains in its early stages, It’s certainly too early to tell if it’s anything more than a buzzword, let alone if its promise will translate into practicality. But the sorts of people who bet on these kinds of things are betting on it.
And why not? Suppose a structure could unfold itself, like origami. Imagine if walls could flex or stiffen in response to shifting loads, or if a buried pipe could change shape to accommodate varying water flows — or to pump water via peristalsis, like your digestive system. Through 4-D printing, nothing is set in stone unless you want it to be.
Hermann Weyl. Photo courtesy ETH-Bibliothek Zurich.
In 1928, the equations of British physicist Paul Dirac helped to describe the workings of the subatomic particles known as fermions. Within a year, other theorists – including a contemporary and schoolmate of Einstein’s named Hermann Weyl – had come up with solutions to Dirac’s equations that meant two other, quite odd types of fermions might also exist.
Proving them right would take some time, and Weyl’s quasiparticle assumed a kind of legendary status until 2015, when three separate teams confirmed its existence (my article says two, but a third popped up after I wrote it). Read on to find out more about this “ghost particle” and how it could transform electronics.
Eduard Piotrowski of Poland’s University of Krakow published the first major blood spatter study in 1895, but its impact was limited to a few inventive European sleuths like German chemist Paul Jeserich and French forensic scientist Victor Balthazard. The American legal system did not adopt spatter analysis as evidence until the landmark case of State of Ohio v. Samuel Sheppard, and the field did not truly take off until the 1970s, after forensics expert Herbert MacDonell published his influential Flight Characteristics of Human Blood and Stain Patterns.
Blood spatter analysis has undergone major refinements in methods and language since then, including a recent and growing shift toward incorporating computers. I discuss several of these shifts in my 2015 update of Shanna Freeman’s 2007 article:
Sacharomyces cerevisiae cells. Image courtesy Wikipedia Photo/Masur.
Researchers from the Stowers Institute for Medical Research and the University of Colorado Boulder have combined two optical systems to get around the natural limits of optical microscopes, which usually cannot see objects smaller than the wavelengths of light. Using this method, the team found that spindle pole bodies in yeast — tiny, tube-shaped structures essential to cell division — duplicate and form some structures at different times than once thought.
(This is one of a series of press releases I am writing for Stowers. They are a bit more technical than my usual articles, but each includes a more widely accessible summary at the end. I hope you’ll check them out!)
Seven to 10 billion years ago, a bunch of galaxies fell in with a bad crowd at the Coma cluster — a galactic group comprising thousands of their ilk. That crash “quenched” the ill-fated galaxies. They’d never again burn with hot, young stars. But the crash should have done more than shut down the unfortunate galaxies’ stellar birth rate. It should have strewn their stars across space.
So what kept these cosmic corpses intact? Read on, if you dare (OK, so the title is a bit of a hint …).
