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| SCIENCE TRIBUNE | Thursday, February 14, 2002, Chandigarh, India |
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Video
conferencing shrinks distances Thumbnail
size silicon pump NEW PRODUCTS &
DISCOVERIES
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Video conferencing shrinks distances VIDEO conferencing is a medium where individuals or groups can meet face-to-face in real time to interact. This type of system provides means for communicating live pictures of conference participants thus expanding the shared visual space. Numerous applications are associated with this field. Teledentistry is an application where the consultants of one area of the country are able to view the patient’s x-rays or MRI scans from a hospital at the other end of the country. This technology is also used to beam back live pictures of road accidents, which enables the accident and emergency department to examine the injured person at the roadside. Video conferencing provides a tremendous boost to the business environment. Today’s businesses are becoming more and more globalised. Video conferencing helps in reducing the cost of travel, cost of accommodation and the time taken to travel. A meeting can be held by many organisations at one time and documents can also be passed around. Video conferencing in education has many applications. In some places where schools do not have many skilled teachers video
conferencing provides students with a simple yet effective method of being taught. The teacher can provide online demonstrations of applications in real time.
Types Single person camera system: A single person camera system (Fig.
1-below) is used to capture a view of conference participants and the resulting video signal is transmitted and displayed at the other end. This system is suitable for situations where the number of participants per conference site is limited to one to three. The system provides visual presence of all conference participants all the time. Voice switched system:
In this system (Fig. 2-below), several person cameras are used to capture pictures of the participants in the conference room. Using the audio signal for switching, only the output of the camera showing the speaker is transmitted and displayed at the other end. The spatial relationship between conference participants is not conveyed. The system provides high resolution for the picture of the speaker at the expense of continuous visual presence. Split screen system:
This system (Fig. 3-below) uses two cameras, each providing a picture with an aspect ratio of 4:1.5. A composite 4:3 ratio is produced and transmitted. Generally at the receiving end, the pictures of the participants are displayed on two monitors providing an effective aspect ratio of 8:1.5. The conference participants are split into two groups, typically three participants in each group. The resulting two pictures are multiplexed in a single vide signal before transmission. At the other end, the picture is split into two and these are displayed side by side. For the same number of participants, this system provides better resolution to convey facial expressions and nonverbal cues than the single person camera system. A spatial relationship between conference participants is very difficult to maintain in this system. Continuous presence system:
Continuous presence system (Fig. 4-below) also ensures the visual presence of all the participants. It does this by dynamic allocation of temporal and spatial resolution to the output of a number of cameras subject to a fixed total bandwidth constraint. In the continuous presence system the conference scene is segmented into n segments. Each segment contains one or two participants and is captured by a video camera. This result in n channel video signals which are all transmitted to the other end. Portions of the available transmission bandwidth are dynamically assigned to different channels based on their resolution requirements.
Fig. 5 (below) illustrates three students present in one room and an expert present somewhere else in the world, involved in video conferencing. The expert (A) sits in a swivel chair in room 1 with three monitors representing the three virtually.
Present participants (B, C and D). These three participants are physically located in room 2 seated at three sides of a square table. A monitor, which provides the virtual presence of the room 1 participant, located on the fourth side of the table. Directly behind this monitor are three cameras angled to capture the images of the three participants from the same vantagepoint that the fourth participant would have if were physically present. The signals from these video cameras pass through three switching units en route to the monitors in room 1. The state of the video switches is based upon the angular position of the viewer’s chair in room 1. A shaft encoder attached to the chair mechanism senses the angular position of the chair. Participants are requested to rotate the chair to look from one monitor to another as opposed to turning their heads or moving their eyes. The day is not far when the internet service provides will start providing users with an affordable alternative to ISDN like ADSL, which will make video conferencing more versatile. |
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Thumbnail size silicon pump Scientists have manufactured a pump the size of a thumbnail, made entirely of silicon, which has a long and extremely reliable service life and an immense potential in the field of biotechnology. Microsystems engineering has added mechanical and optical components to the field of microelectronics. Various chip fabrication techniques, such as the deposition of material or its removal through etching, are used to develop novel micromachines. Semiconductor materials are thereby converted into engineering materials. With these advances in view, Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Munich have developed the silicon miniature pump, a report in Fraunhofer Gesellschaft said. “It isn’t only the ability to use tried-and-tested processing techniques that make this metalloid so attractive to microengineers,” explains Martin Richter from IMS. “Thanks to the materials outstanding elastic properties, we have even manufactured the pump membrane out of silicon.” Consequently, the micromechanical devices show no observable signs of wear of fatigue when working with particle-free fluids, and have a long and extremely reliable service life. A small disc of piezoceramic material is mounted on the membrane and made to oscillate by electrical pulses output by the external control module the size of a matchbox. The vibrating membrane is able to draw in a minute amount of liquid or gas, one hundred times per second, through one valve and expel it through another. In one minute it pumps upto two millilitres and produces upto half a bar of over-pressure.
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NEW PRODUCTS & DISCOVERIES IT’S a plane ... It’s a helicopter ... Actually, it’s a bit of both. The gyroplane, whose concept was first put forward in 1919 by Spanish inventor Juan de la Cierva, has been revived by two Utah-based brothers, David and Jay Groen. They’ve spent 15 years and some $ 40 million perfecting a design they hope will provide a cheaper, simpler, safer alternative to the helicopter. No airport is required. Like a helicopter, the gyroplane takes off almost vertically and can fly 330 miles at a cruising speed of 120 m.p.h. Unlike a helicopter, it has a gas turbinepowered propeller that drives the craft forward and provides airspeed to power two asymmetrical overhead blades. These 42-ft blades rotate only when the wind rushes up through them. They give the aircraft lift, stability and improved safety; in case of engine failure, they continue to rotate and allow a safe, controlled descent. The other thing that makes the gyroplane different from a helicopter is the bottom line: running costs (about $160 per hr.) are almost halved. The gyroplane is in the final stages of FAA testing, and a 13-dealer network is busy targeting tourism and agriculture markets. It might also do service on the homeland-security beat: CEO David Groen says the craft would be ideal for border, pipeline and nuclear-facility surveillance. Availability: Early 2003, for $749,000 To, learn more: www.gbagyros.com Antique device makes
microscope faster Researchers have adapted a centuries old device, spectroscope, for use in fluorescence microscopes which offers the advantage of speedy scanning of an area and holds promise for future use in research. The spectrograph splits white light into separate colours and creates a high level of contrast — effects which are important for use in fluorescence. The biophysicists at Utrecht University, the Netherlands, coupled this device to a computer, allowing them to zoom in and quickly scan a small area as speed is an important factor because many biological processes are over within a few seconds. By testing the spectrograph in the course of research on proteins taken from muscle tissue, the scientists were able to show that illumination led to unexpected chemical reactions. The modern spectrograph is relatively simple. A glass fibre conducts the light from the microscope and through a triangular prism. The prism splits the light into its various component colours, a report in NWO Research Reports said.
PTI An Israeli man has invented a solution for blind people who have difficulty distinguishing between objects that are similar to the touch — “talking stickers”. William Korkosvski, from the northern Israeli town of Naharya, has several blind friends and found they have difficulty distinguishing between products such as beverage bottles, cleaning liquids, cans and CDs, according to the Israeli Ma’ariv daily. “That can even be dangerous, like in the case of an eyedrop bottle and a glue bottle that feel quite similar to the touch,” Ma’ariv quoted Korkosvski as saying. He developed a simple solution: a sticker with a code containing information about the item that is to be attached to every object. When the blind person wants to identify the item, he scans the sticker with a special speaking pen, which says the name of the item out loud, the daily explained. “There are over 20,000 blind people in Israel whom the stickers can help and I have already gotten the state’s agreement to fund half the cost,” Korkovski said. According to Ma’ariv, the “talking stickers” and pen will be on the market in less than two weeks.
DPA How primates camouflage Researchers have discovered the reason behind all primates, apart from humans, in having scleras that are similar in colour to their irises, faces or both, attributing it as a means for camouflaging their gaze from predators. The eyes of humans lack pigmentation in a region around the iris called the sclera — the reason why it is called the “white”. But other primates make pigments to darken the same region of their eyes. The animals have to spend energy for making these pigments. To find an answer as to why the animals take all this trouble, Hiromi Kobayashi and Shiro Koshima of the Tokyo Institute of Technology compared the coloration of the sclera, the iris and the surrounding face in humans and 81 species of primates at the Japan Monkey Centre in Inuyama. The scientists discovered that all primates apart from humans have scleras that are a similar colour to their irises, faces or both with the result, the outlines of either the iris — which indicates where the animal is looking — or the eye itself are effectively camouflaged. The study examined about half of all species of living non-human primates, a report in New Scientist said.
PTI Glowing bandages to alert doctors Smart bandages could soon alert doctors to the presence of certain bacteria in a wound by glowing in different colours. Researchers in the United States have created a tiny device that emits faint of two colours in response to two types of bug, says a report in the international science journal Nature. Most bacteria are either “Gram-positive” or “Gram-negative”. A dye called crystal violet stains Gram-positive bacteria blue-violet and is used today to distinguish the two cell types. Gram-positive bacteria are more susceptible to antibiotics, so the test can be useful for treating infections. Benjamin Miller and his colleagues, of the University of Rochester in New York State, hope to replace the cumbersome staining procedure with a simple process that registers the colour difference instantly and in situ. To develop the sensor, the team collaborated with Philippi Faucher, also at Rochester, a specialist in silicon-based light-emitting devices. Fauchet and the team found that when Gram-negative bacteria stick to the surface of porous silicon, the colour of the light emitted changes slightly. The researchers make the silicon attract Gram-negative, but not gram-positive, by coating it with specially designed molecules that hook chemical groups only present on Gram-negative microbes.
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Science & Technology crossword
Clues Across 1. An economical beam. 4. A material coming under frequent use. 6. A weighed block for striking the material being forged. 8. This welding evolves a temp. of 3600°C 10. A unit of sound absorption by a surface. 12. An important parameter to control quality of concrete. 13. Term for sea coast area falling in a country’s jurisdiction. 15. Made of neat cement and applied to surfaces. 16. Another name for a hinged joint. 17. Corrosion Resistant steel (abbr.) 18. Methane gas of LPG type. 19. Provided below a cooling tower. 20. Provided on windows for safety. 21. An electrically charged particle. 22. An alkali’s atom carrying charge. 23. A finish time used in CPM network (abbr.) 24. Must for proper storage of aggregates. Down 2. Check a column against this. 3. A scientist looks for their best and cheap variety. 5. Protect reinforcement against this. 6. A radiological technique to find age. 7. A technique for taking photographs from air (abbr.) 9. Short for a company. 11. An important design load for tall structures. 13. Short for an engineer. 14. Check a L beam for this also. 15. Used to strengthen steel members. 17. Abbr. for coarse aggregate. Solution to last week’s crossword:
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