Thursday, November 24, 2011
Ultraviolet semiconductor diode lasers are widely used in data processing, information storage and biology. Their applications have been limited, however, by size, cost and power. The current generation of ultraviolet lasers is based on a material called gallium nitride, but Jianlin Liu, a professor of electrical engineering, and colleagues have made a breakthrough in zinc oxide nanowire waveguide lasers, which can offer smaller sizes, lower costs, higher powers and shorter wavelengths.
Until now, zinc oxide nanowires couldn't be used in real world light emission applications because of the lack of p-type, or positive type, material needed by all semiconductors. Liu solved that problem by doping the zinc oxide nanowires with antimony, a metalloid element, to create the p-type material.
The p-type zinc oxide nanowires were connected with n-type, or negative type, zinc oxide material to form a device called p-n junction diode. Powered by a battery, highly directional laser light emits only from the ends of the nanowires.
"People in the zinc oxide research community throughout the world have been trying hard to achieve this for the past decade," Liu said. "This discovery is likely to stimulate the whole field to push the technology further".
Liu's findings have been reported in the recent issue of Nature Nanotechnology Co-authors are: Sheng Chu, Guoping Wang, Jieying Kong, Lin Li and Jingjian Ren, all graduate students at UC Riverside; Weihang Zhou, a student at Fudan University in China; Leonid Chernyak, a professor of physics at the University of Central Florida; Yuqing Lin, a graduate student at the University of Central Florida; and Jianze Zhao, a visiting student from Dalian University of Technology in China.
The discovery could have a wide-range of impacts.
For information storage, the zinc oxide nanowire lasers could be used to read and process much denser data on storage media such as DVDs because the ultraviolet has shorter wavelength than other lights, such as red. For example, a DVD that would store two hours of music could store four or six hours using the new type of laser.
For biology and medical therapeutics, the ultra-small laser light beam from a nanowire laser can penetrate a living cell, or excite or change its function from a bad cell to a good cell. The light could also be used to purify drinking water.
For photonics, the ultraviolet light could provide superfast data processing and transmission. Reliable small ultraviolet semiconductor diode lasers may help develop ultraviolet wireless communication technology, which is potentially better than state-of-the-art infrared communication technologies used in various electronic information systems.
While Liu and the students in his laboratory have demonstrated the p-type doping of zinc oxide and electrically powered nanowire waveguide lasing in the ultraviolet range, he said more work still needs to be done with the stability and reliability of the p-type material.
T-Mobile is soon going to launch a new Android Smartphone known as the Samsung Behold II. Samsung Behold was originally launched as a feature phone but now Samsung has decided to transform the Behold into a full featured Smartphone device.
It will come with Samsung TouchWiz UI featuring a Cube menu, 3.2-inch AMOLED touchscreen display, 5MP camera with Auto focus & Flash, up to 16GB external memory, A-GPS, Wi-Fi, Bluetooth 2.1, music player and Android market.
The Samsung Behold II will be launched into the market this holiday season.
Thursday, November 3, 2011
Satellite internet is a great broadband choice, but it's not the best option for everyone. How do you know if Satellite's right for you? Here are a few questions that will help you decide:
- Do you have access to a telephone line or a cable TV line? For those that aren't plugged into these networks, satellite internet is the way to go. Satellite internet delivers internet access through over-the-air satellite waves, and therefore aren't limited by the physical infrastructure the same way DSL, Cable, and even Fiber Optics broadband services are. That means, for those in remote parts of the world, or those that are in a mobile set-up (e.g. mobile home), satellite internet makes plenty of sense.
- Do you have space for a satellite dish? Sounds obvious, but it's necessary to have space to install an outdoor dish with a clear line-of-sight to the southern sky. If unsure, it might be worth it to consult with a provider's technician on whether your set-up is optimal for satellite service before signing any agreement, especially for multi-story apartment or condominium units.
- Do you live somewhere with inclement weather? On the flipside, the fact that satellite internet is not tied to a physical infrastructure means its subject to connectivity problems with moisture and precipitation in the atmosphere. Heavy storms may even cause prolonged periods of signal outages. It's, therefore, important to take into consideration the normal weather patterns in and around your area.
- Is speed a priority? Satellite internet, while considerably faster than traditional dial-up internet, ranges slower in download/upload speeds relative to other broadband solutions. Consumers can typically get 5mbps at the high-end for satellite service. Compare that to 15+mbps for cable, DSL, and fiber optics services. For casual internet users that require internet to email, browse the web, and chat with friends, satellite internet should be sufficient. But for heavier users, online gamers, those that download lots of media or stream video frequently, and business professionals that require VPN or VoIP connections, it might make sense to look elsewhere. Particularly for hard-core gamers, transmission latency in satellite internet might make for a frustrating experience.
- How much are you willing to spend? With satellite internet access, you get mobility and freedom from physical infrastructures. However, on average, the monthly rate of satellite service per mbps is the most expensive out of all the broadband solutions.
Now Eugenio Culurciello of Yale's School of Engineering & Applied Science has developed a supercomputer based on the human visual system that operates much more quickly and efficiently than ever before. Dubbed NeuFlow, the system takes its inspiration from the mammalian visual system, mimicking its neural network to quickly interpret the world around it. Culurciello presented the results Sept. 15 at the High Performance Embedded Computing (HPEC) workshop in Boston, Mass.
The system uses complex vision algorithms developed by Yann LeCun at New York University to run large neural networks for synthetic vision applications. One idea-the one Culurciello and LeCun are focusing on, is a system that would allow cars to drive themselves. In order to be able to recognize the various objects encountered on the road-such as other cars, people, stoplights, sidewalks, not to mention the road itself-NeuFlow processes tens of megapixel images in real time.
The system is also extremely efficient, simultaneously running more than 100 billion operations per second using only a few watts (that's less than the power a cell phone uses) to accomplish what it takes bench-top computers with multiple graphic processors more than 300 watts to achieve.
"One of our first prototypes of this system is already capable of outperforming graphic processors on vision tasks," Culurciello said.
Culurciello embedded the supercomputer on a single chip, making the system much smaller, yet more powerful and efficient, than full-scale computers. "The complete system is going to be no bigger than a wallet, so it could easily be embedded in cars and other places," Culurciello said.
Beyond the autonomous car navigation, the system could be used to improve robot navigation into dangerous or difficult-to-reach locations, to provide 360-degree synthetic vision for soldiers in combat situations, or in assisted living situations where it could be used to monitor motion and call for help should an elderly person fall, for example.
Other collaborators include Clement Farabet (Yale University and New York University), Berin Martini, Polina Akselrod, Selcuk Talay (Yale University) and Benoit Corda (New York University).
In a paper published this week in Nature Communications, CAIDA researcher Dmitri Krioukov, along with MariÃ¡n BoguÃ±Ã¡ (Universitat de Barcelona) and Fragkiskos Papadopoulos (University of Cyprus), describe how they discovered a latent hyperbolic, or negatively curved, space hidden beneath the Internet's topology, leading them to devise a method to create an Internet map using hyperbolic geometry. In their paper, Sustaining the Internet with Hyperbolic Mapping, the scientists say such a map would lead to a more robust Internet routing architecture because it simplifies path-finding throughout the network.
"We compare routing in the Internet today to using a hypothetical road atlas, which is really just a long encoded list of road intersections and connections that would require drivers to pore through each line to plot a course to their destination without using any geographical, or geometrical, information which helps us navigate through the space in real life," said Krioukov, principal investigator of the project.
Now imagine that a road - or in the case of the Internet, a connection - is closed for some reason and there is no geographical atlas to plot a new course, just a long list of connections that need to be updated. "That is basically how routing in the Internet works today - it is based on a topographical map that does not take into account any geometric coordinates in any space," said Krioukov, who with his colleagues at CAIDA have been managing a project called Archipelago, or Ark, that constantly monitors the topology of the Internet, or the structure of its interconnections.
Like a number of experts, however, Krioukov is concerned that existing Internet routing, which relies on only this topological information, is not really sustainable. "It is very complicated, inefficient, and difficult to scale to the rapidly growing size of the Internet, which is now accessed by more than a billion people each day. In fact, we are already seeing parts of the Internet become intermittently unreachable, sinking into so-called black holes, which is a clear sign of instability".
Krioukov and colleagues have developed an in-depth theory that uses hyperbolic geometry to describe a negatively curved shape of complex networks such as the Internet. This theory appears in paper Hyperbolic Geometry of Complex Networks, published by Physical Review E today. In their Nature Communications paper, the scientists employ this theory, Ark's data, and statistical inference methods to build a geometric map of the Internet. They show that routing using such a map would be superior to the existing routing, which is based on pure topology.
Instead of perpetually accessing and rebuilding a reference list of all available network paths, each router in the Internet would know only its hyperbolic coordinates and the coordinates of its neighbors so it could route in the right direction, only relaying the information to its closest neighbor in that direction, as per the researchers. Known as "greedy routing", this process would dramatically increase the overall efficiency and scalability of the Internet. "We think that using such a routing architecture based on hyperbolic geometry will create the best possible levels of efficiency in terms of speed, accuracy, and resistance to damage," said Krioukov.
However the scientists caution that actually implementing and deploying such a routing structure in the Internet might be as challenging, if not more challenging, than discovering its hidden space. "There are a number of technical and non-technical issues to be resolved before the Internet map that we found would be the map that the Internet uses," said Krioukov.
As per Maxime Darnon, a researcher at the French National Center for Scientific Research, in order to continue increasing the speed of integrated circuits, interconnect insulators will require an upgrade to porous, low-dielectric constant materials. Darnon and his colleagues discuss the details in the Journal of Applied Physics, which is published by the American Institute of Physics (AIP).
"The integration of a replacement, porous SiCOH (pSiCOH), however, poses serious problems such as an unacceptable 'roughening' that occurs during plasma processing," explains Darnon. "This is considered a 'showstopper' to faster integrated circuits at the moment, so a fundamental understanding of the roughening mechanisms that occur during the etch process of integrated circuit manufacturing is highly desirable to material designers and etch-process engineers.
Darnon's research team proposes a mechanism for the roughening of pSiCOH materials etched in a fluorocarbon-based plasma. They've shown that the problematic roughness results from a cracking of the denser top surface under ion bombardment, and that this roughness propagates through a slower etching of the dense top surface than the modified porous material beneath it. Perhaps more importantly, the team recommends ways to minimize this phenomenon so that the "showstopper" will only be a speedbump on the road to faster integrated circuits.
To achieve this, however, the instructor must set the right stage, says University of Michigan professor Perry Samson.
Samson is a professor in the Department of Atmospheric, Oceanic and Space Sciences who has received honors for his educational technology work.
He has developed robust interactive student response system called LectureTools that utilizes students' laptops. A paper about how students report that LectureTools affected their learning is reported in the May edition of the journal Computers & Education.
"If you allow laptops in the classroom without a plan for how you'll use them, you can potentially invite disaster. It's unlikely that students will be so entranced by class material that they won't wander off to their favorite social networking sites," Samson said. "The key is to deliberately engage students through their computers. LectureTools does just that".
LectureTools is an interactive student response system and teaching module. Instructors at more than 400 colleges and universities have set up accounts to use it.
Samson recently surveyed close to 200 students who, over the past three semesters, have taken his Extreme Weather lecture course that utilized LectureTools. Students reported that while they did sometimes stray from in-class tasks, laptops with LectureTools made them feel more attentive, engaged and able to learn, compared with classes that don't use the system.
"Our surveys showed that while laptop computers can be a distraction, students of this generation feel that they are capable of productive multitasking," Samson said.
Through LectureTools, laptops serve as robust "clickers," providing drastically more interaction than the class polling that clicker-based student response systems offer.
LectureTools also allows students to take notes directly on lecture slides. Students can anonymously ask the instructor's aide a question through a chat window during class, and others can see these questions and answers. Students can also rate their own understanding of each slide, giving the professor valuable feedback.
"It is the first successful instance I've seen of dramatic use of information technology to augment the real-time classroom experience," said John King, vice provost for academic affairs and the William Warner Bishop Collegiate Professor of Information. "LectureTools significantly increases the interactivity between the student and the instructor without disrupting the flow of the class. The instructor gets a lot more detailed information about where the students are while maintaining normal operation in the class".
Close to half of students surveyed said that having a laptop in class increased the amount of time they spent on tasks uncorrelation to the lecture. But a full 78 percent agreed that laptops in class made them more engaged. Approximately half said that having their laptops made them more attentive. Seventy percent said laptops had a positive effect on their learning.
LectureTools significantly increased class participation as well. The system allows students to chat with an instructor's aide, posing questions without raising a hand and having to speak up in front of their peers.
"You can ask the dumb question without fear," Samson said.
More than half of the students asked at least one question during the semester, which is a much higher percentage than Samson saw in classes without LectureTools, he said.
The paper is called "Deliberate Engagement of Laptops in Large Lecture Classes to Improve Attentiveness and Engagement".
Of course the use of removable media for backup extends beyond your photo files and should include all files that you consider "must haves."
The "iCare", "Data Recovery 3.6" Software, is a bit more advanced than some past free offerings and deserves a look, particularly since it's free.
Besides the usual data loss recovery feature "iCare's", "Data Recovery 3.6" Software allows you to recover deleted hard drive partitions, perform "deep scan recoveries" and "format recoveries."
Get your free iCare Data Recovery 3.6 Software before the offer is rescinded at midnight tonight.
Take a camera with you whenever possible, and look around, you'll find a picture somewhere.
How does one place an artwork in a particular artistic period? This is the question raised by researchers from the Laboratory of Graphics and Image in the University of Girona and the Max Planck Institute for Biological Cybernetics, in Gera number of. The scientists have shown that certain artificial vision algorithms mean a computer can be programmed to "understand" an image and differentiate between artistic styles based on low-level pictorial information. Human classification strategies, however, include medium and high-level concepts.
Low-level pictorial information encompasses aspects such as brush thickness, the type of material and the composition of the palette of colours. Medium-level information differentiates between certain objects and scenes appearing in a picture, as well as the type of painting (landscape, portrait, still life, etc.). High-level information takes into account the historical context and knowledge of the artists and artistic trends.
"It will never be possible to precisely determine mathematically an artistic period nor to measure the human response to a work of art, but we can look for trends", Miquel Feixas, one of the authors of the study, reported in the journal Computers and Graphics, tells SINC.
The scientists analysed various artificial vision algorithms used to classify art, and observed that certain aesthetic measurements (calculating "the order" of the image based on analysing pixels and colour distribution), as well as the composition and diversity of the palette of colours, can be useful.
The team also worked with people with little knowledge of art, showing them more than 500 paintings done by artists from 11 artistic periods. The participants were "surprisingly good" at linking the artworks with their corresponding artistic period, showing the high capacity of human perception.
Beyond the implications for philosophy and art, the researchers want to apply their research in developing image viewing and analysis tools, classifying and searching for collections in museums, creating public informative and entertainment equipment, and in order to better understand the interactions between people, computers and works of art.
Beauty, order and complexity
The earliest work of this kind was done in 1933, when the mathematician George D. Birkhoff tried to formalise the notion of beauty with an aesthetic measurement defined as the relationship between order and complexity. After this, the philosopher Max Bense converted this into a measurement of information based on entropy (disorder or diversity).
As per Bense, the creative process is a selective process ("to create is to select"), within a range of elements (a palette of colours, sounds, phonemes, etc.). The creative process can be seen as channel for transmitting information between the palette and the artist and the objects or features of an image. This concept provides a powerful tool for analysing composition and the visual attention ("saliency") of a painting.