June 25, 2013 ? The universe is awash in terahertz (THz) waves, as harmless as they are abundant. But unlike other regions of the electromagnetic spectrum, THz has proven to be extremely difficult to manipulate in order to capture novel images of objects and materials with which these light waves interact.
Most existing THz imaging devices employ prohibitively expensive technology or require several hours and cumbersome manual controls in order to generate a viable image, according to Boston College Professor of Physics Willie J. Padilla.
Padilla and researchers in his lab recently reported a breakthrough in efforts to create accessible and effective THz imaging. Using both optical and electronic controls, the team developed a single-pixel imaging technique that uses a coded aperture to quickly and efficiently manipulate stubborn THz waves, according to a recent report in the journal Optics Express.
In the so-called terahertz gap, a region of wavelengths that falls between microwave and infrared frequencies, conventional electronic sensors and semiconductor devices are ineffective. Some systems capture only a fraction of a scene and the means to tune these THz waves are inefficient. This has fueled the search for new imaging technologies in order to manipulate THz waves.
Efforts to overcome the challenges of mechanics, cost and image clarity are viewed as a crucial step in efforts to tame the THz gap since imaging and sensing at this frequency holds the potential for advances in areas as divergent as chemical fingerprinting, security imaging of hidden weapons, even real-time skin imaging to promote simple detection of skin cancer.
Central to this challenge is the development of a technology to create efficient masks -- similar to the aperture of a camera -- capable of tuning THz radiation in order to produce clear images in just a few seconds.
Padilla and graduate students David Shrekenhamer and Claire M. Watts report their new single pixel imaging method centers on what they describe as a "coded aperture multiplex technique" where a laser beam and electronic signals are used to send a set of instructions to a semiconductor so it can guide the reproduction of the image of an object after THz waves have passed through it.
A digital micro-mirror device encodes the laser beam with instructions that direct certain segments of the silicon mask to react and allow a selected sample of the THz waves to pass freely through, consistent with the image pattern. The combination of optical instructions and the reaction of the semiconductor create a THz spatial light modulator, the team reports. Functioning like the aperture of a conventional camera, the modulator then guides the digital reconstruction of the entire image based on a broad sampling of THz waves that have passed through the object.
The team's experiments found the method could produce masks of varying resolutions, ranging from 63 to 1023 pixels and acquire images at speeds up to .5 Hz, or about 2 seconds. The early findings "demonstrate the viability of obtaining real-time and high-fidelity THz images using an optically controlled SLM with a single pixel detector," the team concluded.
Padilla said the findings have spurred additional research by his lab into ways to further control THz waves, such as by using the intricate patterns of an engineered metamaterial to further manipulate terahertz waves to create images faster and with increased efficiency.
After spending a few days roasting over an open fire, Paula Deen is cooked. She lost her job with the Food Network on Friday meaning that she is, for all intents and purposes, gone from our lives now. But an unusual voice spoke up in her defense last night: professional opinioner Bill Maher. Eater pointed us towards this video of Maher defending the former Food Network star on last night's?Real Time with Bill Maher. ...
How To Select The Perfect Home Based Business Today, many people are taking advantage of the flexible work and turning to home based businesses which means there are plenty of opportunities and options for those who want to start a home based business. One of the first steps towards having success with a home based [...]
The post How To Select The Perfect Home Based Business appeared first on Free PLR.
College basketball: Ex-UA staffer trying to put NAU on track Arizona Daily Star Olson himself was at Murphy's home debut last season in Flagstaff and as a show of support for the Lumberjacks program, former Arizona Wildcats star Andre Iguodala bought season tickets. The moral of the story? Once a Wildcat, always a Wildcat. Read ?
Sen. Rob Portman's (R-Ohio) vote against bipartisan background checks legislation followed him home during the congressional recess, with protests at his events and a request for a meeting from the mother of a gun violence victim.
Portman declined to meet with Jerri Jackson of Springfield, Ohio, who lost her son in the mass shooting in Aurora, Colo. and wanted to explain why she supports background checks. His office cited scheduling conflicts.
?I would like for him to at least sit down and talk to me,? Jackson told the Associated Press. "To hear my story and hear the heartbreak of a mother who lost her son in the prime of his life. How guns have played a part in our lives, but it is what ended his life. We need to do something about it."
Jackson told reporters that she believes expanded background checks may have prevented James Holmes, who had a record of mental health issues, from obtaining firearms -- including an assault rifle and high capacity magazines.
?Assault rifles have no place on the streets of America,? Jackson said. ?If he did not have that high-powered magazine, he would not have been able to shoot as many people as he did as quickly as he did.?
Portman was one of the lawmakers who voted against the amendment from Sens. Joe Manchin (D-W.Va.) and Pat Toomey (R-Pa.) to strengthen and expand background checks for gun sales.
After casting his no vote, Portman argued that the Manchin-Toomey amendment would not have been "effective in preventing the kind of heartbreaking loss of life seen in Newtown or in other recent tragic incidents." Instead, he believed the bill would have made it "difficult for law-abiding Ohioans to exercise their Constitutionally-guaranteed rights."
Sens. Kelly Ayotte (R-N.H.), Richard Burr (R-N.C.) and Jeff Flake (R-Ariz.) also declined to meet with the families of gun violence victims while home for recess.
In a poll released last week by Democratic firm Public Policy Polling, Portman was one of a number of senators that have seen their approval ratings drop in the wake of voting no on the background check bill; Portman's approval was down 18 points.
In a poll released by Quinnipiac University on the Friday after the defeat of Manchin-Toomey, 84 percent of Ohioans said they favored universal background checks.
AMSTERDAM (AP) ? Justin Bieber wrote an entry into a guestbook at the Anne Frank House museum in Amsterdam, saying he hoped the Jewish teenager who died in a Nazi concentration camp "would have been a Belieber" ? or fan of his ? if history were different.
The message triggered a flood of comments on the museum's Facebook page Sunday, with many criticizing the 19-year-old Canadian pop star for writing something they perceive to be insensitive.
Calls made and emails sent to Bieber's publicist and agent in Los Angeles weren't immediately returned.
Museum spokeswoman Maatje Mostart confirmed that Bieber visited Friday evening. She said the museum was happy to have received Bieber and didn't see anything offensive in his remarks.
Anne Frank hid with her family in a small apartment above a warehouse during the Nazi occupation of World War II. Her family was caught and deported, and Anne died of typhus in Bergen-Belsen in 1945.
The diary she kept in hiding was recovered and published after the war, and has become the most widely read document to emerge from the Holocaust.
Bieber's whole note read: "Truly inspiring to be able to come here. Anne was a great girl. Hopefully she would have been a Belieber."
Mostart said Bieber called ahead and was given a guided tour.
Bieber's remarks led to criticism from some quarters, as a Facebook response insulting Bieber received more than 1,000 "likes" ? slightly more than the museum's original post about the incident.
Meanwhile on Twitter, posts mocking Bieber and imagining that he had visited the museum and walked away thinking only of himself began circulating Sunday, though the message is open to interpretation.
Some of Bieber's 37 million followers also tweeted messages of support. Others in his fan base ? which is heavily weighted toward young girls ? tweeted that they didn't know who Anne Frank was.
Frank was 13 years old when she began keeping her diary in 1942. Like many teenage girls, she made a collage of the celebrities of her day ? movie stars, dancers, and royalty ? and kept it on her bedroom wall.
"Our little room looked very bare at first with nothing on the walls; but thanks to Daddy who had brought my film-star collection and picture postcards ... with the aid of a paste pot and brush, I have transformed the walls into one gigantic picture," she wrote on July 11, 1942, just days after going into hiding. "This makes it look much more cheerful."
Many of those pictures can still be seen on the walls of the museum Bieber visited Friday.
Bieber has had a tough few weeks in Europe. He had to leave a monkey in quarantine after landing in Germany without the necessary papers for the animal. Before that, the 19-year-old singer had a trying stay in London. The star struggled with his breathing and fainted backstage at a show, was taken to a hospital and then was caught on camera clashing with a paparazzo. Days earlier, he was booed by his fans when he showed up late to a concert.
He performed in Arnhem, Netherlands, on Saturday night, and will next perform three nights in Oslo, Norway.
Getting to the root of horseradish root problemsPublic release date: 15-Apr-2013 [ | E-mail | Share ]
Contact: Susan Jongeneel sjongene@illinois.edu 217-333-3291 University of Illinois College of Agricultural, Consumer and Environmental Sciences
URBANA Approximately 55 percent of the horseradish produced in the United States is grown in the Collinsville, Ill., area, the self-proclaimed "Horseradish Capital of the World." The product is of such high quality that Europeans import it for gourmet and industrial use. But when crop sciences professor Mohammad Babadoost first arrived at the University of Illinois in 1999, he was told that growers had been experiencing significant yield reductions due to internal discoloring and root rot.
"If the roots are discolored, they are not accepted for processing," Babadoost said.
U of I researchers have been looking at various bacteria and fungi for more than 30 years, trying to identify the agents causing the problem. In the 1980s, they isolated a fungus called Verticillium dahlia, which was linked to horseradish disease at many locations in the United States.
Babadoost, however, was not convinced that this fungus alone was responsible for all the damage.
"When I came here, I realized that it's a serious problem, and I thought it could be a complex problem rather than a single-pathogen/single-disease problem," he said.
He was right. In 2004, he and his team determined that internal discoloration of horseradish roots is due to a disease complex caused by at least three fungi: Verticillium dahlia, Verticillium longisporum, and Fusarium solani.
"But I was still not completely convinced that that was the end of the story," he said. He was seeing a lot of root rot that did not appear to be caused by the identified pathogens.
He and his graduate student, JunMyoung Yu, carried out fungal isolations from horseradish roots from commercial fields in Illinois and Wisconsin. They first identified isolates to genus; those identified as Fusarium were further identified to species based on their morphological and molecular characteristics.
They selected 11 isolates that they identified initially as Fusarium oxysporum. After further analysis, they found that six of them were actually Fusarium commune, a species that was identified in 2003.
To compare the pathogenicity of the two species, they inoculated asymptomatic horseradish roots with either F. commune or F. oxysporum and monitored root quality at monthly intervals.
They found that plants inoculated with F. oxysporum developed internal root discoloration. However, roots inoculated with F. commune had more discoloration, and 83 percent of them developed root rot by four months after inoculation. This was the first time that F. commune had been linked to horseradish disease.
Knowing the source of the disease, however, does not solve the problem. Although infected roots can be dug up, washed, and replanted, the process is labor-intensive, and the plants remain susceptible to the pathogens that remain in the soil.
Babadoost said that growers are interested in developing resistant cultivars, but doing so will not be an easy task. "I don't know if cultivars resistant to the internal root discoloration will ever be available because of the complexity of the disease," he said. "You have to go through a long process of testing against each individual pathogen and combination of pathogens to come up with a reasonably resistant cultivar."
He recommends that growers use an Integrated Pest Management (IPM) approach. Infected roots can be cleaned in hot water and replanted. Biocontrol agents or fungicides can be used to protect the roots from infection for 12 weeks, and it takes roughly the same amount of time for root damage to reach unacceptable levels.
"If these two techniques are combined, by the end of the season in the fall the roots are either not infected or discoloration from infection is negligible, so you can sell the roots," he said.
###
The research is described in "Occurrence of Fusarium commune and F. oxysporum in Horseradish Roots" by J. M. Yu and M. Babadoost, which was published by the American Phytopathological Society in the April 2013 issue of Plant Disease and can be accessed at http://dx.doi.org/10.1094/PDIS-06-12-0538-RE.
[ | E-mail | Share ]
?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Getting to the root of horseradish root problemsPublic release date: 15-Apr-2013 [ | E-mail | Share ]
Contact: Susan Jongeneel sjongene@illinois.edu 217-333-3291 University of Illinois College of Agricultural, Consumer and Environmental Sciences
URBANA Approximately 55 percent of the horseradish produced in the United States is grown in the Collinsville, Ill., area, the self-proclaimed "Horseradish Capital of the World." The product is of such high quality that Europeans import it for gourmet and industrial use. But when crop sciences professor Mohammad Babadoost first arrived at the University of Illinois in 1999, he was told that growers had been experiencing significant yield reductions due to internal discoloring and root rot.
"If the roots are discolored, they are not accepted for processing," Babadoost said.
U of I researchers have been looking at various bacteria and fungi for more than 30 years, trying to identify the agents causing the problem. In the 1980s, they isolated a fungus called Verticillium dahlia, which was linked to horseradish disease at many locations in the United States.
Babadoost, however, was not convinced that this fungus alone was responsible for all the damage.
"When I came here, I realized that it's a serious problem, and I thought it could be a complex problem rather than a single-pathogen/single-disease problem," he said.
He was right. In 2004, he and his team determined that internal discoloration of horseradish roots is due to a disease complex caused by at least three fungi: Verticillium dahlia, Verticillium longisporum, and Fusarium solani.
"But I was still not completely convinced that that was the end of the story," he said. He was seeing a lot of root rot that did not appear to be caused by the identified pathogens.
He and his graduate student, JunMyoung Yu, carried out fungal isolations from horseradish roots from commercial fields in Illinois and Wisconsin. They first identified isolates to genus; those identified as Fusarium were further identified to species based on their morphological and molecular characteristics.
They selected 11 isolates that they identified initially as Fusarium oxysporum. After further analysis, they found that six of them were actually Fusarium commune, a species that was identified in 2003.
To compare the pathogenicity of the two species, they inoculated asymptomatic horseradish roots with either F. commune or F. oxysporum and monitored root quality at monthly intervals.
They found that plants inoculated with F. oxysporum developed internal root discoloration. However, roots inoculated with F. commune had more discoloration, and 83 percent of them developed root rot by four months after inoculation. This was the first time that F. commune had been linked to horseradish disease.
Knowing the source of the disease, however, does not solve the problem. Although infected roots can be dug up, washed, and replanted, the process is labor-intensive, and the plants remain susceptible to the pathogens that remain in the soil.
Babadoost said that growers are interested in developing resistant cultivars, but doing so will not be an easy task. "I don't know if cultivars resistant to the internal root discoloration will ever be available because of the complexity of the disease," he said. "You have to go through a long process of testing against each individual pathogen and combination of pathogens to come up with a reasonably resistant cultivar."
He recommends that growers use an Integrated Pest Management (IPM) approach. Infected roots can be cleaned in hot water and replanted. Biocontrol agents or fungicides can be used to protect the roots from infection for 12 weeks, and it takes roughly the same amount of time for root damage to reach unacceptable levels.
"If these two techniques are combined, by the end of the season in the fall the roots are either not infected or discoloration from infection is negligible, so you can sell the roots," he said.
###
The research is described in "Occurrence of Fusarium commune and F. oxysporum in Horseradish Roots" by J. M. Yu and M. Babadoost, which was published by the American Phytopathological Society in the April 2013 issue of Plant Disease and can be accessed at http://dx.doi.org/10.1094/PDIS-06-12-0538-RE.
[ | E-mail | Share ]
?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
??
![[ Back to EurekAlert! ]](http://www.eurekalert.org/images/back2e.gif){kind=small}
Public release date: 15-Apr-2013
Share ]