For Star Wars fans, Princess Leia’s holographic message to Obi-Wan Kenobi asking for help is a pivotal moment in the 1977 Star Wars film Episode IV: A New Hope.
But it is only now that the technology enabling her desperate plea stands a chance of becoming a reality.
Engineers have created stretchable holograms that can change from one image to another, offering the tantalizing possibility that holographic videos may one day be possible.
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The researchers calculated how much a holographic image expands as the material generating it stretches, and how far the image plane moves away from its original position.
Based on these findings, the team created multi-layered holograms made up of two or three different images.
This means that as the surface stretches, one image appears in the place of another.
Using this method, they created a hologram that showed a pentagon in its relaxed state, which transformed into a square, and then a triangle when pulled.
Scientists from the Department of Materials Science and Engineering (SEAS) at the University of Pennsylvania used metasurfaces – flat, ultra-thin surfaces – to make their holograms.
They built on their previous work in creating 3D and multi-color holograms by embedding tiny gold rods in a stretchable film.
This helped them understand how holographic images change with stretching and to see if they could use this information to create a hologram that can switch between images.
Altai in southern Siberia sits right at the centre of Russia. But the tiny, mountainous republic has a claim to fame unknown until now – Native Americans can trace their origins to the remote region.
DNA research revealed that genetic markers linking people living in the Russian republic of Altai, southern Siberia, with indigenous populations in North America.
A study of the mutations indicated a lineage shift between 13,000 and 14,000 years ago – when people are thought to have walked across the ice from Russia to America
This roughly coincides with the period when humans from Siberia are thought to have crossed what is now the Bering strait and entered America.
“Altai is a key area because it’s a place where people have been coming and going for thousands and thousands of years”, said Dr Theodore Schurr, from the University of Pennsylvania.
Among the people who may have emerged from the Altai region are the predecessors of the first Native Americans.
Roughly 20-25,000 years ago, these prehistoric humans carried their Asian genetic lineages up into the far reaches of Siberia and eventually across the then-exposed Bering land mass into the Americas.
“Our goal in working in this area was to better define what those founding lineages or sister lineages are to Native American populations,” Schurr said.
The region lies at the intersection of what is now Russia, Mongolia, China and Kazakhstan.
Dr Schurr’s team checked Altai DNA samples for markers in mitochondrial DNA which is always passed on by mothers, and Y chromosome DNA which sons inherit from their fathers.
“At this level of resolution we can see the connections more clearly,” Schurr said.
Looking at the Y chromosome DNA, the researchers found a unique mutation shared by Native Americans and southern Altaians in the lineage known as Q.
Mitochondrial DNA is found in tiny rod-like ‘powerplants’ in cells that generate energy. Both kinds of DNA showed links between Altaians and Native Americans.
In the Y chromosome DNA, the researchers found a unique mutation shared by Native Americans and people from southern Altai.
The findings are published today in the American Journal of Human Genetics.
Calculating how long the mutations they noted took to arise, Schurr’s team estimated that the southern Altaian lineage diverged genetically from the Native American lineage 13,000 to 14,000 years ago, a timing scenario that aligns with the idea of people moving into the Americas from Siberia between 15,000 and 20,000 years ago.
Though it’s possible, even likely, that more than one wave of people
crossed the land bridge, Schurr said that other researchers have not yet been able to identify another similar geographic focal point from which Native Americans can trace their heritage.
“It may change with more data from other groups, but, so far, even with intensive work in Mongolia, they’re not seeing the same things that we are”, he said.
In addition to elucidating the Asia-America connection, the study confirms that the modern cultural divide between southern and northern Altaians has ancient genetic roots
Attribution: Daily Mail