Scientists twist radio beams to send data: Transmissions reach speeds of 32 gigibits per second

Graphic showing the intensity of the radio beams after twisting.
Credit: Courtesy of Alan Willner / USC Viterbi

Building on previous research that twisted light to send data at unheard-of speeds, scientists at USC have developed a similar technique with radiowaves, reaching high speeds without some of the hassles that can go with optical systems.

The researchers, led by electrical engineering professor Alan Willner of the USC Viterbi School of Engineering, reached data transmission rates of 32 gigabits per second across 2.5 meters of free space in a basement lab at USC.

For reference, 32 gigabits per second is fast enough to transmit more than 10 hour-and-a-half-long HD movies in one second and is 30 times faster than LTE wireless.

"Not only is this a way to transmit multiple spatially collocated radio data streams through a single aperture, it is also one of the fastest data transmission via radio waves that has been demonstrated," Willner said.

Faster data transmission rates have been achieved -- Willner himself led a team two years ago that twisted light beams to transmit data at a blistering 2.56 terabits per second -- but methods to do so rely on light to carry the data.

"The advantage of radio is that it uses wider, more robust beams. Wider beams are better able to cope with obstacles between the transmitter and the receiver, and radio is not as affected by atmospheric turbulence as optics," Willner said.

Willner is the corresponding author of an article about the research that will be published in Nature Communications on Sept. 16. The study's co-lead authors Yan Yan and Guodong Xie are both graduate students at USC Viterbi, and other contributors came from USC, the University of Glasgow, and Tel Aviv University.

To achieve the high transmission rates, the team took a page from Willner's previous work and twisted radio beams together. They passed each beam -- which carried its own independent stream of data -- through a "spiral phase plate" that twisted each radio beam into a unique and orthogonal DNA-like helical shape. A receiver at the other end of the room then untwisted and recovered the different data streams.

"This technology could have very important applications in ultra-high-speed links for the wireless 'backhaul' that connects base stations of next-generation cellular systems," said Andy Molisch of USC Viterbi. Molisch, whose research focuses on wireless systems, co-designed and co-supervised the study with Willner.

Future research will focus on attempting to extend the transmission's range and capabilities.

The work was supported by Intel Labs University Research Office and the DARPA InPho (Information in a Photon) Program.

Source: University of Southern California

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How widespread is tax evasion? Cost of 'round-tripping,' a method investors use to avoid the tax collector

A new study puts a cost on "round-tripping," a method investors use to avoid the tax collector.
Credit: Illustration: Jose-Luis Olivares/MIT

Tax evasion is widely assumed to be an eternal problem for governments -- but how widespread is it? For the first time, a new study, co-authored by an MIT professor, has put a cost on a particular kind of tax evasion, known as "round-tripping," that the U.S. government has been trying to thwart.

In round-tripping, U.S. investors move funds to offshore tax havens, then invest in U.S. equity and debt markets with these "foreign" funds. In essence, the U.S. investors are disguising themselves as foreign investors, who are not subject to the same tax rates on capital gains and interest income. The money is said to have made a "round trip" since it originates in the U.S., and winds up back in U.S. markets.

According to the study, published in the Journal of Finance, every 1 percent increase in the top U.S. tax rate leads to an increase of 2.1 percent to 2.8 percent in foreign portfolio investment (FPI) from tax havens. As of 2008, some $34 billion to $109 billion of FPI from those havens appears to have been invested in the U.S. via round-tripping, leading to a loss of $8 billion to $27 billion in tax revenue.

"The higher the tax rate, the more securities appear to be purchased from tax haven jurisdictions," says Michelle Hanlon, a professor of accounting at MIT. "This seems to indicate that U.S. individuals are pretending to be foreigners who then invest in the U.S. markets."

The paper, "Taking the Long Way Home: U.S. Tax Evasion and Offshore Investments in U.S. Equity and Debt Markets," is co-authored by Hanlon, Edward L. Maydew of the University of North Carolina, and Jacob R. Thornock of the University of Washington.

Hanlon and her co-authors have presented their findings to the staff of the U.S. Senate's Permanent Subcommittee on Investigations, among other groups interested in the results.

A subtle strategy for identifying evaders

To be sure, not all investments from tax havens are dubious, so the study employed a multiprong strategy. First, it looked at changes in investment levels from tax havens after changes in U.S. tax rates. Second, the study evaluated these changes in investment with an eye to whether or not the U.S. has a bilateral Tax Information Exchange Agreement (TIEA) with the offshore sovereignty in question. TIEAs potentially allow the U.S. to find out considerably more information about the investments being made from those locations.

Sure enough, the researchers found that there is a decrease of up to 32 percent, in both equity and debt investments, when the U.S. creates a TIEA with other sovereign parties.

"The reverse effect we see is that when the U.S. enters into an exchange agreement, we see less investment from tax havens," adds Hanlon, who is the Howard W. Johnson Professor of Accounting at the MIT Sloan School of Management.

To be clear, Hanlon says, "It's very hard to identify tax evasion, because obviously people are trying to hide it." However, she adds, "Once we started seeing the data, we realized we could try to tackle this problem. We had to do a lot of tests to try to isolate the effect we're looking for, [and] we think it's a big step to try to put some numbers around this phenomenon."

The conclusions come from data collected by both the U.S. Federal Reserve and the U.S. Treasury, which allowed the researchers to piece together monthly flows of foreign investment into U.S. equity and debt markets.

Policy changes: What can be done?

Hanlon suggests that greater international cooperation will at least make this type of tax evasion more difficult and riskier. Additional TIEAs, for instance, would force some investors to go to greater lengths to engage in round-tripping.

"People always try to evade taxes, but [more TIEAs] will make it harder," Hanlon suggests. "And the more costly and risky it becomes, the costs will outweigh the benefits, at least on the margin, and the less likely people are to do it."

On the academic front, Hanlon recognizes that the study's findings present a wide range for the total cost of this tax evasion, but hopes the paper will be a spur to other scholars who may want to delve into the same topic.

"We felt it was important enough that someone try to do research like this, to get people thinking about other data sources and other ways to examine [tax evasion]," Hanlon says. 

"Our hope was that it would lead to more research and that people would take more risks to look at things like this."

Source: Massachusetts Institute of Technology

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Cheaper 3-D virtual reality system: Powerful enough for a gamer, made for an engineer

It's like a scene from a gamer's wildest dreams: 12 high-definition, 55-inch 3D televisions all connected to a computer capable of supporting high-end, graphics-intensive gaming.
Credit: Image courtesy of Brigham Young University

It's like a scene from a gamer's wildest dreams: 12 high-definition, 55-inch 3D televisions all connected to a computer capable of supporting high-end, graphics-intensive gaming.

On the massive screen, images are controlled by a Wii remote that interacts with a Kinnect-like Bluetooth device (called SmartTrack), while 3D glasses worn by the user create dizzying added dimensions.

But this real-life, computer-powered mega TV is not for gaming. It's for engineering.

Welcome to Brigham Young University's VuePod, a 3D immersive visualization environment run by BYU's Department of Civil and Environmental Engineering. Student-built and operated, under the supervision of civil engineering professor Dan Ames, the VuePod is changing the way engineers are viewing environmental engineering challenges.

"This is gold," said fellow BYU civil engineering professor Kevin Franke. "This technology has the ability to revolutionize my job as an earthquake engineer."

That's because the VuePod allows users to virtually fly over, wander through or hover above 3D environments that are otherwise difficult to visit. The images are created by point data from aircraft equipped with LIDAR (think RADAR, but with lasers). The LIDAR scans the landscape and records millions of data points that are then viewed as an image on the VuePod. Point data can also be created from stitched-together photographs taken from low-cost drones, which is Franke's research focus.

One set of data currently available for study in the VuePod captured a canyon area beneath a plateau in southern Idaho. With 3D glasses and the Wii controller, a user can virtually drop down into the canyon from above, and then fly from one end to the other.

As cool as it is to fly through a canyon, the real engineering application comes in when you combine two sets of data for the same canyon, taken five years a part. With the second set of data, changes in the natural landscape that are invisible to the human eye become clear as day. Thanks to the VuePod's massive 108-square-foot screen, all of the image-making data can be presented for viewing.

"Our eyes and our brains are so amazing; we need to take full advantage of them," Ames said. "That's the value of this project: we're presenting more information for the human eyes to detect changes."

In addition to natural change detection, the VuePod has the potential to assist in infrastructure monitoring -- such as tracking how highways hold up (or slough and crack) over time and seeing the affect on buildings after severe weather or earthquakes.

While the VuePod is certainly not the first immersive visualization system in academia, it may just be the most cost efficient built to date. Some systems cost as much as $10 million to build and maintain, while BYU's VuePod just barely topped the $30,000 mark.

Ames details how BYU was able to build such a powerful system for so little in a new paper published by the Journal of Computing in Civil Engineering.

"Our question has been: How can we make this technology accessible?" Ames said. "We're trying to determine the threshold for getting the most function at the most affordable cost. Ultimately, the goal is to take an expensive tool and make it cheaper for an everyday engineering firm to use."

And even though Ames and his students have achieved that, they believe much more can be done.

"We want whoever reads this paper to be able to build a better system than we built," he said.

Source: Brigham Young University

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The Data mining disaster: Computer technology can mine data from social media during disasters

Computer technology that can mine data from social media during times of natural or other disaster could provide invaluable insights for rescue workers and decision makers, according to an international team writing in the International Journal of Emergency Management.

Adam Zagorecki of the Centre for Simulation and Analytics, at Cranfield University, Shrivenham, UK and David Johnson of Missouri State University, Springfield, USA and Jozef Ristvej of the University of Zilina, Zilina, Slovakia, explain that when disaster strikes the situation can change rapidly. Whether that is during flooding, landslide, earthquake or terrorist attack, understanding the complexities of the situation can mean the difference between saving human and animal lives, reducing environmental impact and preventing major economic loss.

The team points out that advances in information technology have had a profound impact on disaster management. First, these advances make unprecedented volumes of data available to decision makers. This, however, brings with it the problem of managing and using that data. The team has surveyed the state of the art in data mining and machine learning in this context. They have found that whereas earlier applications were focused on specific problems, such as modeling the dispersion by wind of plumes -- whether from a chemical plant leak, fire or nuclear incident -- and monitoring rescue robots, there are much broader applications, such as constructing situational awareness and real-time threat assessment.

Data mining during a disaster can pull in information from unstructured data from news reports, incident activity reports, and announcements, as well as structured textual data from emergency services, situational reports and damage assessment forms. In addition, it can utilize remote sensing data, as well as more frequently now, mobile phone images and video, and satellite and aerial images.
Critically, the team also reveals that the advent of social media is playing an important role in generating a real-time data stream that grows quickly whenever disaster strikes and those involved have access to wireless communications and or internet connectivity. In particular, data mining of social media can assist with the response phase of disaster management. This information can quickly provide data points for models that are not available in conventional simulations.

"Disasters often undergo rapid substantial evolution; therefore, disaster management is a non-uniform process characterized by phases, although these phases are not distinct in nature," the team reports, they have now highlighted the challenges and hinted at future trends that might improve disaster response through the use of modern data mining technology.


Source: Inderscience

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