Ring brings ancient Viking, Islamic civilizations closer together

Article by Bruce Bower

Inscription, style and lack of wear point to rare archaeological evidence of contact

More than a century after its discovery in a ninth century woman’s grave, an engraved ring has revealed evidence of close contacts between Viking Age Scandinavians and the Islamic world.

Excavators of a Viking trading center in Sweden called Birka recovered the silver ring in the late 1800s. Until now, it was thought that it featured a violet amethyst engraved with Arabic-looking characters. But closer inspection with a scanning electron microscope revealed that the presumed amethyst is colored glass (an exotic material at the time), say biophysicist Sebastian Wärmländer of Stockholm University and his colleagues.

An inscription on the glass inset reads either “for Allah” or “to Allah” in an ancient Arabic script, the researchers report February 23 in Scanning.

Scandinavians traded for fancy glass objects from Egypt and Mesopotamia as early as 3,400 years ago (SN: 1/24/15, p. 8). Thus, seagoing Scandinavians could have acquired glass items from Islamic traders in the same part of the world more than 2,000 years later rather than waiting for such desirable pieces to move north through trade networks.

Ancient texts mention encounters around 1,000 years ago between Scandinavians and members of the Islamic civilization, which stretched from West Asia to Mediterranean lands. Archaeological evidence supporting those accounts, though, is rare.

The inner surface of the Birka ring’s silver body shows virtually no signs of wear. Filing marks made in the final stage of its production are still visible. That suggests that the ring made by an Arabic silversmith had few or no owners before it reached the Viking woman, the researchers say.

Fully transparent solar cell to turn every window into a power source

Technology is so advanced now that there are solar panels that can make every window and screen a power source in your home. Are you up on the solar panel technology?

There is a transparent solar concentrator that can turn any window or sheet of glass into a photovoltaic solar cell. Other ‘transparent’ solar cells are not truly transparent, this is truly transparent. Richard Lunt, who led the research at Michigan State University, says the team team are confident that the solar panel can be deployed in a range of settings, from tall buildings with a lot of windows or a mobile device that needs high aesthetic quality like a phone or an e-reader.

A transparent solar panel is like an oxymoron because solar panels are usually dark in color. They are usually made the fro photovoltaic kind, which makes energy by absorbing sunlight and converting into electricity. If the material is transparent, but, by definition it means that the light passes through the medium to strike the back of your eye. This is why previous transparent solar panels have actually only been partially transparent.

Organic salts absorb UV light and infrared, and emit infrared – processes that occur outside of the visible spectrum, so that it appears transparent. To be able to get around this little knot, Michigan State researchers used a different technique for gathering sunlight. They did not use a transparent photovoltaic cell, they use a transparent luminescent solar concentrator.

The TLSC consists of organic salts hat absorb specific non-visible wavelengths of ultraviolet and infrared light, which then will be luminesced as another wavelength of infrared light. This emitted infrared light is guided to the edge of plastic, where strips of conventional photovoltaic solar cell convert it into electricity.

Michigan’s TLSC is currently had the efficiency of around 1 percent, but they think 5 percent should be possible. Non-transparent luminescent concentrators max out around 7 percent. Researchers are confident that this technology can be scaled from large industrial and commercial applications, down to consumer devices while still remaining “affordable.”

One of the larger barriers to solar power is the intrusive and ugly nature of solar panels – obviously, if our scientists can produce enough solar power from sheets of glass and plastic that looks like normal glass and plastic, then it would be huge.





Humans may harbor more than 100 genes from other organisms

Article by Sarah C. P. Williams

You’re not completely human, at least when it comes to the genetic material inside your cells. You—and everyone else—may harbor as many as 145 genes that have jumped from bacteria, other single-celled organisms, and viruses and made themselves at home in the human genome. That’s the conclusion of a new study, which provides some of the broadest evidence yet that, throughout evolutionary history, genes from other branches of life have become part of animal cells.

“This means that the tree of life isn’t the stereotypical tree with perfectly branching lineages,” says biologist Alastair Crisp of the University of Cambridge in the United Kingdom, an author of the new paper. “In reality, it’s more like one of those Amazonian strangler figs where the roots are all tangled and crossing back across each other.”

Scientists knew that horizontal gene transfer—the movement of genetic information between organisms other than parent-to-offspring inheritance—is commonplace in bacteria and simple eukaryotes. The process lets the organisms quickly share an antibiotic-resistance set of genes to adapt to an antibiotic, for instance. But whether genes have been horizontally transferred into higher organisms—like primates—has been disputed. Like in bacteria, it’s been proposed that animal cells could integrate foreign genetic material that’s introduced as small fragments of DNA or carried into cells by viruses. But proving that a bit of DNA in the human genome originally came from another organism is tricky.

Crisp and his colleagues analyzed the genome sequences of 40 different animal species, ranging from fruit flies and roundworms to zebrafish, gorillas, and humans. For each gene in the genomes, the scientists searched existing databases to find close matches—both among other animals and among nonanimals, including plants, fungi, bacteria, and viruses. When an animal’s gene more closely matched a gene from a nonanimal than any other animals, the researchers took a closer look, using computational methods to determine whether the initial database search had missed something.

In all, the researchers pinpointed hundreds of genes that appeared to have been transferred from bacteria, archaea, fungi, other microorganisms, and plants to animals, they report online today in Genome Biology. In the case of humans, they found 145 genes that seemed to have jumped from simpler organisms, including 17 that had been reported in the past as possible horizontal gene transfers.

“I think what this shows it that horizontal gene transfer is not just confined to microorganisms but has played a role in the evolution of many animals,” Crisp says, “perhaps even all animals.

The paper doesn’t give any hints as to how the genes—which now play established roles in metabolism, immune responses, and basic biochemistry—may have been transferred or the exact timeline of the jumps, he says. That will take more work.

The findings are critical to understanding evolution, says Hank Seifert, a molecular biologist at the Northwestern University Feinberg School of Medicine in Chicago, Illinois. “This is a very well-done paper. They used all the latest data they could find, all the genomes in the databases,” he says. “It makes it clearer than ever that there has been a history, throughout evolution, of gene transfer between organisms.”

But not all agree that the new evidence is indisputable. “I see little here that is particularly convincing evidence for horizontal gene transfer,” says microbiologist Jonathan Eisen of the University of California, Davis. He doesn’t rule out that horizontal gene transfer between bacteria and animals is possible, but says that there are other explanations for the identified genes being present in only some branches of the evolutionary tree—a gene that existed in a far-off ancestor could have simply been lost in many relatives other than two seemingly unrelated species, for instance. “It is up to [the researchers] to exclude other, more plausible alternatives, and I just do not think they have done that.”

*Correction, 16 March, 12:37 p.m.: The piece has been updated to clarify the fact that bacteria are not eukaryotes.