Butterfly Wing Optics Help to Cheaply Create Bright, Realistic Holograms


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Butterfly Wing Optics Help to Cheaply Create Bright, Realistic Holograms

University of Utah electrical and computer engineering associate professor Rajesh Menon shows off a new 2D hologram that can be displayed with just a flashlight. His team has discovered a way to create inexpensive full-color 2D and 3D holograms that are far more realistic, brighter, and can be viewed at wider angles than current holograms.

Credit: Dan Hixson/University of Utah College of Engineering

Holograms have long captured the public’s imagination. Whether it’s Star Wars fans dreaming of holographic messages and chess games, concertgoers standing in awe before a resurrected Tupac Shakur, or theholographic future envisioned in the upcoming Blade Runner 2049, the hologram concept seems to offer something for everyone.

But despite the development of modern, laser-based hologram technology since the 1960s, the only holograms most of us encounter today are the blurry security images on our credit cards or the occasional dimly lit display in a science museum.

Now a team of engineers from the University of Utah claims to have developed a game-changing technology that can cheaply create photorealistic 3D holograms that are viewable with nothing more than a flashlight. In a paper published in Scientific Reports, the researchers explain how they used complex 3D nanostructures to produce holograms with the kind of rich colors and bright display that may one day make sophisticated holograms an everyday reality.

To understand how today’s hologram technology works, it’s helpful to compare it to regular photographs. A photographic camera uses lenses and a natural light source to record the light emitted from a scene on a photographic medium. The result is a 2D image that faithfully matches the original scene from a specific angle or vantage.

RELATED: Nano-Hologram Technology Will Bring 3D Images to Phones, Tablets, and TVs

A hologram, however, is a recording of the full light field produced by an object in three dimensions. To capture that scattered light field requires a powerful light source like a laser, which is split and directed by mirrors to strike the object from all sides.

Ordinary holograms record the light field on a chemical medium similar to photographic paper, which to the naked eye looks like nothing more than a random collection of dots and lines. To actually produce the holographic image, you need to shine another laser light on or through the recorded hologram. The resulting ghost-like, floating image can then be viewed from many angles.

Conventional hologram technology has some serious limitations, according to Rajesh Menon, associate professor of electrical and computer engineering at the University of Utah and lead author of the new paper. First, the holograms produced by these laser-based systems are very dim and only clearly visible in dark rooms. Second, if you want a hologram with many colors, you need to use lasers in each color, which quickly gets expensive. Then there are issues with the mass-produced sticker-style holograms used for security, which are distorted by a rainbow shimmering effect.

The new process developed by Menon and his team appears to solve all of these issues while greatly reducing the production and display costs. The magic is in the holographic recordings, which are transparent sheets of plastic embossed with a 3D nanostructure of microscopic hills and valleys. Instead of absorbing white light and only reflecting back certain wavelengths, the nanoscale topography of the hologram is engineered to manipulate and tune light so that it produces a bright, full-color 3D image from the simple beam of a flashlight.

The technology is similar to an evolutionary adaptation exhibited in certain butterfly species. Color in nature is usually a product of pigments that absorb certain wavelengths of light and reflect others. But these butterflies boost the brilliance of their iridescent wings by bouncing light across microscales instead of absorbing it. As some wavelengths are canceled out through interference, a brilliant pure blue is reflected back to the viewer.

RELATED: A Nanotech Breakthrough Could Generate True Holograms

Menon explained that his computer-generated microstructures serve a similar purpose, increasing the efficiency and brightness of the hologram by redirecting light rather than absorbing it.

“We take all the colors of light that come in and essentially displace them slightly,” he said. “Let’s say we’re creating an American flag. I want the red here, the blue there, and I want white everywhere else. I can design my structure to essentially displace the colors very efficiently.”

Since the 3D nanostructures can be stamped onto normal plastic, the holograms will be relatively affordable to reproduce, similar to the mass-production of CDs or DVDs. That could help Menon’s holograms compete in the security market. Instead of the rainbow-streaked stickers on credit cards and driver’s licenses, we could soon have photorealistic holograms that are much more difficult to forge.

While the paper only describes the production of 2D holograms, Menon says that his team has also successfully made static 3D holograms using the same technology. But he hasn’t taken his sight off the ultimate goal, which is a full-motion interactive hologram straight out of sci-fi. He said that this initial research points to a path forward, but that many engineering challenges remain.

“To create dynamic images, you need to be able to change the pattern that you’re imprinting as a function of time,” Menon said. “There are technologies that we can borrow upon to do this, but they need some improvement.”

Menon has launched a private company called PointSpectrum to continue developing the hologram technology, which he hopes will soon compete with bulky virtual reality headsets in providing immersive holographic experiences at theme parks, movie theaters, schools, and more.

Originally published on Seeker.

Ebola May Linger in Men’s Semen for More Than 2 Years


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Ebola May Linger in Men’s Semen for More Than 2 Years

Particles of Ebola virus (Zaire) obtained from cell culture fluid.

Credit: Elena Ryabchikova, Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Science

Ebola may linger in men’s semen for more than two years, a new study suggests.

What’s more, at least one man who survived Ebola and then tested negative for the presence of the virus in his semen later tested positive, the new study found.

The findings raise questions about how long Ebola can linger in special immune hideouts in the body. However, the new findings only show some men carry RNA or genetic material from Ebola long after recovering from the disease. They don’t necessarily mean all men who test positive for Ebola RNA are still capable of transmitting the virus. [What Are the Long-Term Effects of Ebola?]

Ebola virus is a rare and deadly virus that starts with common flu-like symptoms, such as fever, muscle and joint pain, and headache, according to the Centers for Disease Control and Prevention. As the virus progresses, however, people suffer from extreme diarrhea and vomiting, and in the late stages of the disease, people’s blood vessels may become leaky, causing bleeding from the rectum, nose or mouth. People infected with the virus can transmit it through bodily fluids — such as blood, vomit, diarrhea or semen — and are infectious only once they start showing symptoms of the disease. Between 2014 and 2016, there were nearly 30,000 cases of Ebola reported in Sierra Leone, Guinea and Liberia,according to the World Health Organization. Many of the people who survive the initial deadly phase of the disease may still face lingering problems, such as headache, vision problems, fatigue, joint pain and hearing loss, a 2015 study in the New England Journal of Medicine found.

The finding that Ebola can linger in semen even after men recover from the infection is not a surprise to researchers. Studies of men in Sierra Leone, Liberia and Guinea after the 2014-2016 Ebola outbreak found that anywhere from 28 percent to 100 percent of men harbored the RNA, or genetic material, from the Ebola virus in their semen up to three months after infection. Another study found that a minority of men who contracted the virus tested positive for Ebola in their semen seven to nine months after recovering from the infection. In 2015, scientists reported that a man who had recovered from the disease six months earlier hadtransmitted Ebola to a sexual partner.

The World Health Organization currently recommends that people who recover from the virus be tested for any lingering presence of Ebola RNA three months after recovering, and then again until the test is negative on two consecutive monthly tests. If men have not been tested, they should abstain from sex for 12 months, or use condoms every time they have sex, according to WHO guidelines.

Another study found that a man transmitted the virus to his partner more than 500 days after he began showing symptoms of the illness.

But exactly how long does the virus linger in reservoirs in the body — and for how long can it be transmitted?

To answer that question, Dr. William Fischer II, a critical care specialist at the University of North Carolina at Chapel Hill, and colleagues analyzed semen donated by 149 men who had recovered from the virus up to almost three years earlier.

They found that 13 of these men tested positive for the presence of Ebola RNA; 11 of these men had recovered more than two years earlier. One of the 13 men tested positive for Ebola RNA after having tested negative on two prior occasions, the researchers reported July 22 in the journal Open Forum Infectious Diseases. The men who tested positive for Ebola virus in their semen were, on average, older than men who never tested positive. In addition, they were likelier to report the post-Ebola symptoms of vision problems and fatigue, compared with men who tested negative, the study found.

The significance of the findings is still not clear, the researchers noted in the paper.

“While the persistence of EBOV [Ebola virus] RNA in semen is concerning, it is not known if the detection of EBOV RNA in genital fluids is a surrogate for the presence of infectious virus,” the researchers wrote in the paper.

But the prolonged presence of Ebola virus RNA in men should prompt organizations to rethink their sexual transmission prevention guidelines, the researchers wrote. Further research should aim to eliminate Ebola that may be hiding in these reservoirs, the authors added.

One possibility is that Ebola may hide in specific spots in the body that are somewhat protected from the immune system, such as the eye and the testes, the researchers wrote. These “privileged” areas of the body are less prone to inflammatory attack by the immune system when foreign substances are found. The fact that men who reported vision issues after their recovery were likelier to harbor Ebola RNA seems to bolster this notion, the researchers wrote.

As people age, perhaps their immune system becomes less robust, the researchers suggested. Their weakened immune systems may enable the Ebola virus to hide out in these certain immune-privileged sites, such as the testes.

However, figuring out how to provide new information on how to prevent the sexual transmission of Ebola, without making things worse for Ebola survivors, could prove tricky, the researchers noted.

“For many survivors, the physical manifestations of the disease have been compounded by the stigma encountered with their return to their communities,” the researchers wrote in their paper. “Survivor messaging regarding viral persistence, if demonstrated, must provide information that can be used to protect loved ones but at the same time not risk further ostracizing by society.”

Originally published on Live Science.

The Battle of Mosul


Post 8462

The Battle of Mosul

https://www.bostonglobe.com/news/bigpicture/2017/07/12/the-battle-mosul/XERuknxg6cCIB7TVdMwAvN/story.html?p1=BP_Headline

Iraqi government declared the city of Mosul liberated on July 9th, after a nine-month offensive to retake the city. Since October, the forces in Mosul have faced the toughest fighting in the 3-year war against the Islamic State fighters in Iraq. Entire neighborhoods have been destroyed and Amnesty International called the battle a ‘‘civilian catastrophe,’’ with more than 5,800 civilians killed in the western part of the city. The gruelling battle displaced nearly 900,000 from their homes. Sporadic fighting continues in the Old City, signaling the presence of militants still in the area.
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Iraqi Counter-Terrorism Service (CTS) members stand amid destroyed buildings in the old city of Mosul on July 7, during the Iraqi government forces’ offensive to retake the city from Islamic State (IS) group fighters. (AHMAD AL-RUBAYE/AFP/Getty Images)
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An Iraqi man comforts a relative, who fled the fighting between government forces and Islamic State (IS) group jihadists in the Old City of Mosul, as they wait to be relocated in the city’s western industrial district, on July 8. (FADEL SENNA/AFP/Getty Images)
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An Iraqi forces sniper looks on as smoke billows, following an airstrike by US-led international coalition forces targeting Islamic State (IS) group, in the Old City of Mosul on July 8. Part of the battle has been declared accomplished, while other forces continue to fight Islamic State (IS) jihadists in the city. (AHMAD AL-RUBAYE/AFP/Getty Images)
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Iraq’s federal police members wave Iraq’s national flag as they celebrate in the Old City of Mosul on July 9 after the government’s announcement of the “liberation” of the embattled city. (FADEL SENNA/AFP/Getty Images)
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Iraqi federal policemen stand in a damaged building as Iraqi forces continue their fight against Islamic State militants in parts of the Old City of Mosul, Iraq, July 9. (Felipe Dana/Associated Press)
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A general view of the destruction in Mosul’s Old City on July 9. (AHMAD AL-RUBAYE/AFP/Getty Images)
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A member of Iraq’s federal police kisses a girl as forces celebrate in the Old City of Mosul on July 9 after the government’s announcement of the “liberation” of the embattled city. (FADEL SENNA/AFP/Getty Images)
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Members of the Iraqi federal police forces celebrate in the Old City of Mosul on July 10, after the government’s announcement of the victory against the Islamic State fighters. Iraqi Prime Minister Haider al-Abadi’s office said he was in “liberated” Mosul to congratulate “the heroic fighters and the Iraqi people on the achievement of the major victory”. (FADEL SENNA/AFP/Getty Images)
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Iraqis celebrate the occasion of the liberation of Mosul in Tahrir Square in Baghdad, Iraq, July 9. (ALI ABBAS/EPA)
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Members of the Iraqi forces in the Old City of Mosul on July 10, during the offensive to retake the embattled city from Islamic State (IS) group fighters. (FADEL SENNA/AFP/Getty Images)
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An Iraqi woman, who fled the fighting between government forces and Islamic State (IS) group jihadists in the Old City of Mosul, sits while being comforted by another in the city’s western industrial district awaiting to be relocated, on July 8. (FADEL SENNA/AFP/Getty Images)
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A general view of the destruction in Mosul’s Old City on July 9. (AHMAD AL-RUBAYE/AFP/Getty Images)
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An Iraqi woman, who fled the fighting between government forces and Islamic State (IS) group jihadists in the Old City of Mosul, reacts as she sits in the city’s western industrial district awaiting to be relocated, on July 8. (FADEL SENNA/AFP/Getty Images)
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Airstrikes target Islamic State positions on the edge of the Old City a day after Iraq’s prime minister declared “total victory” in Mosul, Iraq, July 11. (Felipe Dana/Associated Press)

The Battle of Mosul


Post 8461

The Battle of Mosul

https://www.bostonglobe.com/news/bigpicture/2017/07/12/the-battle-mosul/XERuknxg6cCIB7TVdMwAvN/story.html?p1=BP_Headline

Iraqi government declared the city of Mosul liberated on July 9th, after a nine-month offensive to retake the city. Since October, the forces in Mosul have faced the toughest fighting in the 3-year war against the Islamic State fighters in Iraq. Entire neighborhoods have been destroyed and Amnesty International called the battle a ‘‘civilian catastrophe,’’ with more than 5,800 civilians killed in the western part of the city. The gruelling battle displaced nearly 900,000 from their homes. Sporadic fighting continues in the Old City, signaling the presence of militants still in the area.
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Displaced children evacuate a neighborhood in West Mosul during the government-led offensive to retake Iraq’s second largest city from Islamic State (IS) group jihadists, on March 16. (ARIS MESSINIS/AFP/Getty Images)
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Iraqi federal police inspect the inside of Mosul’s heavily damaged museum on March 8. Most of the artifacts inside the building appeared to be completely destroyed. The basement level that was the museum’s library had been burned. The floors were covered in the ashes of ancient manuscripts, in western Mosul, Iraq. (Khalid Mohammed/Associated Press)
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U.S. soldiers from the 82nd Airborne Division fire artillery in support of Iraqi forces fighting Islamic State militants from their base east of Mosul on April 17. U.S.-led coalition support for Iraqi ground forces in Mosul repeatedly proved to be the critical factor in the Mosul fight. (Maya Alleruzzo/ Associated Press)
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A girl and her father cry as the family flees the al-Rifai neighborhood while Iraqi special forces battle Islamic State militants in western Mosul, Iraq. The U.N. children’s agency, UNICEF, warned on June 5, that the children in Mosul are bearing the brunt of the intensified fight between U.S.-backed government forces and IS in the city’s western half. (Maya Alleruzzo/ Associated Press)
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A bomb explodes behind the al-Nuri mosque complex, as seen through a hole in the wall of a house, as Iraqi Special Forces move toward Islamic State militant positions in the Old City of Mosul, Iraq, June 29. (Felipe Dana/Associated Press)
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A suspected Islamic State fighter sits in a basement as Iraqi forces continue their advance against Islamic State militants in the Old City of Mosul, Iraq, July 3. Islamic State militants managed to launch a counterattack that reversed days of Iraqi army territorial gains in just a matter of hours. (Felipe Dana/Associated Press)
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Iraqi forensics team personnel inspect the bodies of victims at a site believed to be an apparent airstrike carried out by US forces three weeks ago at al-Shifa district, western Mosul, Iraq, July 5. (OMAR ALHAYALI/EPA)
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A member of the Iraqi Counter-Terrorism Service (CTS) flashes the victory sign from the window of a humvee during an advance in the old city of Mosul on July 5, as the Iraqi government forces continue their offensive to retake the city from Islamic State (IS) group fighters. (AHMAD AL-RUBAYE/AFP/Getty Images)
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A view of the damage in the old city of Mosul on July 7, as Iraqi government forces continue to fight Islamic State (IS) group jihadists to retake the last parts of the city. (AHMAD AL-RUBAYE/AFP/Getty Images)
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Fleeing Iraqi civilians sit inside a house as they wait to be taken out of the Old City during fighting between Iraqi forces and Islamic State militants in Mosul, Iraq, July 8. (Felipe Dana/Associated Press)
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Members of the Iraqi Counter-Terrorism Service (CTS) advance in the Old City of Mosul on July 6, during the Iraqi government forces’ ongoing offensive to retake the city from Islamic State (IS) group fighters. (AHMAD AL-RUBAYE/AFP/Getty Images)
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Fleeing Iraqi civilians walk past the heavily damaged al-Nuri mosque as Iraqi forces continue their advance against Islamic State militants in the Old City of Mosul, Iraq, July 4. (Felipe Dana/Associated Press)
continue on post 8462………

The Battle of Mosul


Post 8460

The Battle of Mosul

https://www.bostonglobe.com/news/bigpicture/2017/07/12/the-battle-mosul/XERuknxg6cCIB7TVdMwAvN/story.html?p1=BP_Headline

Iraqi government declared the city of Mosul liberated on July 9th, after a nine-month offensive to retake the city. Since October, the forces in Mosul have faced the toughest fighting in the 3-year war against the Islamic State fighters in Iraq. Entire neighborhoods have been destroyed and Amnesty International called the battle a ‘‘civilian catastrophe,’’ with more than 5,800 civilians killed in the western part of the city. The gruelling battle displaced nearly 900,000 from their homes. Sporadic fighting continues in the Old City, signaling the presence of militants still in the area.

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Iraqi families, who were displaced by the ongoing operation by Iraqi forces against jihadists of the Islamic State group to retake the city of Mosul, are seen gathering on an area near Qayyarah on October 24, 2016. (BULENT KILIC/AFP/

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A Peshmerga convoy drives toward the frontline in Khazer, about 30 kilometers (19 miles) east of Mosul, Iraq on Oct. 17, 2016. (Bram Janssen/ Associated Press)
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Iraqi army soldiers raise their weapons in celebration on the outskirts of Mosul, Iraq on Oct, 20, 2016. The Iraqi forces prepared for nearly three years to rebuild their military to have enough troops and clear enough supply lines to launch an attack on Mosul. (Associated Press)
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An Iraqi special forces soldier looks at a part of Mosul controlled by Islamic State fighters in Iraq, Nov.15, 2016. (GORAN TOMASEVIC/Reuters)
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Iraqi security officers place a suspected Islamic State group member into the back of a waiting pickup truck, in east Mosul on Feb. 21. A secretive Iraqi intelligence unit is leading the hunt for IS sleeper cells in liberated Mosul. (John Beck/Associated Press)
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Residents carry the bodies of several people killed during fights between Iraq security forces and Islamic State on the western side of Mosul, Iraq on March 24. The levels of destruction are dramatically different between Mosul’s east and west. Many of the east’s residential neighborhoods suffered relatively little damage. In the west, however, entire city blocks are damaged or destroyed by months of airstrikes and artillery. (Felipe Dana/Associated Press)
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Federal Police Rapid Response Forces fire a rocket towards Islamic State positions near the Old City, in Mosul, Iraq, March 20. (Felipe Dana/ Associated Press)
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A woman holds her daughters as gunshots are heard in a neighborhood recently liberated by Iraqi security forces in western Mosul, Iraq on March 14. (Felipe Dana/Associated Press)
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An injured man is carried atop an Iraqi special forces armored vehicle during fighting against Islamic State militants in western Mosul, Iraq on March 14. (Felipe Dana/Associated Press)
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A boy rides his bike past destroyed cars and houses in a neighborhood recently liberated by Iraqi security forces, on the western side of Mosul, Iraq, March 19. (Felipe Dana/Associated Press)

Continue reading “The Battle of Mosul”