What makes hair curly?

Every day is a curly hair day for sheep. But wrapped up in those curls may also be answers to a long-standing mystery: exactly how a strand of hair winds itself into a curl on the cellular level. For many years, there were two competing theories to explain what makes hairs curl in sheep. A study published recently in the Journal of Experimental Biology finds that neither theory is exactly correct. But it remains likely that differences between certain cells on a hair may explain what makes a sheep's wool curly. And while human hair has some crucial differences from wool, understanding why curls happen in one mammal's hair could eventually shed light on others. Researchers led by Duane Harland clipped samples from six New Zealand merino sheep.

They were testing two ideas about curliness. The first theory is that as a curling strand is constructed, the cells on one side divide more quickly than those on the other. This would generate a curve in the direction of the side with fewer cells. The other involves the differences between the two types of cells that make up wool fibres: orthocortical cells and paracortical cells. In this theory, a certain proportion of longer cells to shorter cells, generates a curl. They found that there are not fewer cells on the inside of a curve than on the outside, which countered the first theory. But when they tested the second theory, they found that simply knowing the ratio of long cells to short ones did not allow them to precisely predict a fibre's curl. What they did find was that in any given strand, any orthocortical cell will always be longer than any paracortical.


Age-map of Milky Way

The first large-scale age-map of the Milky Way shows that a period of star formation lasting around four billion years created the complex structure at the heart of our galaxy. The Milky Way is a spiral galaxy with a bulge at the centre that contains about a quarter of the total mass of stars. Previous studies have shown that the bulge hosts two components: a population of metal-poor stars that have a spherical distribution, and a population of metal-rich stars that form an elongated bar with a 'waist', like an x or a bi-lobed peanut. However, analyses of the ages of the stars to date have produced conflicting results.

Now, an international team led by astronomers from the European Southern Observatory (ESO) have analysed the colour, brightness and spectral information on chemistry of individual stars to produce the age-map of the Milky Way. The team has used simulated and observed data for millions of stars from the VISTA Variables in the Via Lactea infrared survey of the inner Milky Way and compared them with measurements of the metal content of around 6,000 stars across the inner bulge from a spectroscopic survey carried out with the GIRAFFE spectrograph on the ESO Very Large Telescope.

Tracing the path

Have you ever wondered how a tiny bacterium enters your body from the surroundings and causes havoc? It does so in two way: it either wiggles around with the help of flagellum to propel itself or uses its body weight to propel itself. So, what path does it trace when it moves? In a study published in Journal of Fluid Mechanics, researchers from Indian Institute of Technology Bombay have created a working model and have traced the path of one such bacteria with flagella - Escherichia coli. The researchers have visualised its motion in a fluid medium and have observed that the bacterium follows two types of helical paths - a larger one and a smaller one. These movements help the bacterium move in the various medium at different paces.

Interstellar Empires

If a superpower were to rule over the entirety of the universe, they would quickly find themselves drowning in logistical nightmares. What challenges might arise in that reality, and how could they be conquered or avoided altogether? That hypothetical scenario forms the basis of Interstellar Empires, an informative documentary from science and futurism filmmaker Isaac Arthur. Interstellar Empires debates the logistics of the seemingly far-fetched ideas presented in novels and video games, digs into their minutia, and provides a dizzying whirl of fascinating tangents along the way. Arthur explains how many of today's technologies and accepted scientific theories could provide the seeds for this imagined future. To watch the documentary, visit

A new state of matter

Physicists have identified a new state of matter whose structural order operates by rules more aligned with quantum mechanics than standard thermodynamic theory. Physicists generally classify the phases of matter as ordered, such as crystal, and disordered, such as gases, and they do so on the basis of the symmetry of such order, said Cristiano Nisoli, leader of the theoretical group that collaborated with an experimental group at the University of Illinois at Urbana-Champaign, USA.

In the new research, the team explored a particular artificial spin ice geometry, called Shakti spin ice. While these materials are theoretically designed, this time, the discovery of its exotic, out-of-equilibrium properties proceeded from experiments to theory.

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