Cybersurfing with Amar Chandel
Instant text messages
AFTER Hotmail, Indians have earned quite a reputation for coming up with user-friendly software, solutions and services. Worthy of that trust is www.unimedia.net , a site maintained by Bangalore-based Graycell Applied Technologies Pvt Ltd.

Science Quiz
by J. P. Garg

Monitoring the computer monitor
by T.M.S. Virdi

AS we spend more and more time on the computer, we have to be careful about the strain that a monitor puts on our eyes. Choosing a wrong monitor might result in severe headaches and loss of eyesight. But, who is the best guide to guide you to purchase and use a correct monitor when hundreds of different companies are tossing thousands of different models in the market? The answer is — you! The customer, who is going to use the monitor. However, a proper knowledge of the technical jargons (related to the monitor) that you might face while purchasing a monitor is always helpful.

Companies which make (or assemble) the monitor are growing at an alarming rate. Are these companies providing what they claim? There is no definite yes or no to this question. The reasons are many.

One thing you’ll discover about monitor quality is that one person’s fuzzies are another person’s perfect display. To a degree, display clarity has to do with individual differences in eyesight. But it has much more to do with what people use the computer for and what they’re willing to accept. The same holds true for audio equipment, of course. One person hears every bit of distortion on the system, while others may not detect any problems at all. For monitors, if you think your display is a fuzzy, or imprecise, or aggravating in any other way, then the display is a problem. What makes a display fuzzy, distorted or otherwise bad in the first place? The manufacturer of the monitor will probably tell you that the problem is the video card and vice versa. And certainly the video card determines the display quality to a degree. But, if you think more logically the problem usually lies with the monitor itself, a complex device in which any number of things can go wrong. Worse still, what “wrong” might in fact be designed right in.

If you look at the today’s monitors, the cathode ray tube (CRT) monitor is the oldest type of display and still the most common. The CRT is essentially a vacuum tube whose face, the glass front, is coated with phosphor compounds. In the CRT, negatively charged electrons are shot by a cathode toward the face of the tube, where they collide with the phosphor coating. The coating converts the enormous energy of the electrons into light, creating the image you see on your screen. The electron guns are one of the four main elements that determine the quality of the image. The others are the shadow mask (replaced in some monitors by an aperture grill), the phosphors that make up the coating on the face of the tube and the face itself.

In general, colour CRTs have three electron guns, while monochrome CRTs have one. Some colour CRTs actually have a single gun consisting of three cathodes, but the idea is the same. Since most users today buy colour monitors, I’ll try to define them only. The guns are arranged in a triangular pattern and each gun emits the electrons in a beam that will hit a three dot or three stripe pattern on the face. The electrons would all just hit the centre of the display if left on their own, so the CRT uses electromagnets around the edge of the tube that force the beam to sweep across the display. The magnets guide all three of the beams at the same time (they’re fired together) and all three beams hit the same three dot or three stripe pattern.

The beam traverses the display face one line of pixels at a time (lines are also called scanlines). At a resolution of 1,024 by 768, for instance, each line contains 1,024 pixels and there are 768 lines that must be drawn each time by the electron guns. When die beam reaches the end of a line, it moves quickly to the beginning of the next line, in an action called a horizontal retrace. When it reaches the end of the final line (the bottom right corner of the display), it moves back to the first line (at the top left) in an action called a vertical retrace.

The electron beam is one possible source of fuzziness. The larger the screen, the wider the angle from the absolute centre, the beam must traverse in order to paint the edges of the display. In the centre the beam is circular, but the angle causes it to become increasingly oval as it nears the edges, just as when you shine a flashlight on a wall at an angle. The result is a distortion called astigmatism. If you see a monitor — especially a larger one (over 15 inches — with fuzziness along the edges of the display, this is possibly what is happening. Manufacturers, of course, continue to develop ways to attempt to eradicate this problem.

When the electrons hit the phosphor compound, the compound glows. This glowing, which happens for varying lengths of time and in different colour patterns, is essentially what you’re seeing when you look at your monitor. The glowing appears in different colours because a colour CRT contains not one but three separate phosphor compounds. The three compounds are arranged together on the screen in three dot patterns or three stripe patterns, each dot consisting of a red, green and blue dot and each stripe consisting of a red, green and blue line. The three dot patterns are called triads or, more popularly, picture elements. (The term picture element is frequently shortened to pixel or, in the television industry, pel.) To display red, green or blue, the electrons strike only one dot in the triad. Other colours result from striking two or three of the dots of a pixel, using varying intensities. The space between dots of the same colour, which is consistent across the display face, is known as the dot pitch.

Among the most annoying and headache-inducing factors in working with monitors is flicker. The two factors involved in flicker, are phosphor persistence and refresh rate. Phosphor persistence refers to the length of time the phosphor glows after the electron beam hits it. The electron beam paints the image to the screen at a rate of at least 60 times per second, or 60 Hertz — double the rate for television. It’s important that the phosphors persist (or keep glowing) long enough to bridge the gap between these paintings. If they don’t, you get flicker. (Note: If the glowing lasts too long, however, you get a ghost image that remains on the screen.)

Flicker is especially a concern with interlaced displays, in which the electron guns effectively cheat. In non-interlaced displays, the image is painted line by line from the top of the screen to the bottom, then repainted again from the top. Interlacing involves painting the screen in two stages — the odd numbered lines and then the even numbered lines. In effect, you get half the image to begin with, then the half filling in the empty line — during the next firing of the guns. Interlaced monitors can be made less expensively, because they demand less precision and less speed (and thus contain less expensive components), but many people can perceive the trickery, in the form of flicker.

But flicker is only one possible factor that can undermine the quality of a display. Another is convergence, whose name arises from the need for the trio of electron beams to hit each pixel precisely or to converge on it. A monitor that is not manufactured properly or in fact not adjusted properly, can fail at this requirement; the result will be images in which only partial pixels are illuminated. To the user, this means the fuzzies. You should pay special attention to convergence claims when buying a monitor, because imperfect convergence can be the most significant problem in display clarity. Test the monitor by running a programme that displays text in your favourite typeface and font size, and carefully examine the clarity of the text in the centre of the display a pattern versus that as you near the corners. An even better test is to display of identical horizontal or vertical stripes and check the centre and edges that way. Or load a favourite graphic, one that occupies the entire screen and that you’ve seen numerous times, and examine its appearance in all locations. If the corners are blurred, then you probably have a convergence problem. Some monitors let you adjust convergence, but be careful of what you’re doing. It’s easy to make a permanently bad adjustment. Many monitors now offer warranties that cover convergence problems for the lifetime of the monitor, but again, make sure nothing has happened to the unit during shipping by testing for the fuzzies.

Shadow masks

Of course, a badly aimed trio of electron beams doesn’t simply fail to illuminate a specific pixel. It also possibly illuminates an adjacent pixel, thereby producing an even poorer display. Many CRTs use a device called a shadow mask (also called a dot mask) to combat this problem while Trinitron displays (developed by Sorry) use an aperture grille instead and some newer displays from NEC, Panasonic and Philips use what is essentially a combination of the two.

The shadow mask sits inside the CRT just behind the face and it’s made up of a metal sheet with tiny holes carefully punched in it (see illustration 1). The holes act as guides for the electron beams so that they strike the correct dots precisely. The holes prevent the beams from accidentally illuminating adjacent pixels, thereby offering a more precise image. But shadow masks limit how much of a beam actually strikes the phosphor compound and also restrict the strength of the beam. These limitations can make the display too dim. Some phosphors will be prevented from glowing and if the beam is too strong, the temperature of the mask increases and the mask expands slightly, producing fuzziness.

Aperture grilles consist of a phosphor pattern of stripes rather than dots on the display face. Each stripe contains phosphors for all three primary colours — red, green and blue while the grille consists of an array of slots that run vertically between a series of thin wires, from the top of the grille to the bottom. Like the holes in the shadow mask, the slots both restrict and position the electron beams as they make their way to the display face. Instead of dot pitch aperture grille monitors refer to screen pitch, the distance between successive stripes of the same colour, and slot pitch, the distance between the slots. The only real display issue with the aperture grille is that it is held in place by thin wires running horizontally behind the display, which are often visible to the user. Aperture grilles can also loosen over time, causing some distortion.

The newer NEC and Panasonic and Philips displays offer neither a shadow mask nor an aperture grille, but a kind of hybrid called a slot mask. The slot mask consists of oval shaped holes that allow more of the electron beams to reach the phosphors, thereby resulting in a brighter display. The only real distortion potential stems from the oval shapes, but since electron beams grow increasingly oval as they near the sides and corners of the display, the shapes don’t produce new forms of fuzziness but only exacerbate existing distortion possibilities.

The electronic controls that are part of the monitor determine how the beams from the electron guns move through the deflection system and strike the phosphors, adjusting for the constantly differing angles and paths taken by the beams on their way to the display face. Often, however, the controls can lose their adjustment, resulting in a distorted overall shape of the display. Barrel distortion causes the top and side edges to appear rounded outward, instead of straight up and down for the side edges and straight across for the top and bottom edges. The opposite of barrel distortion is pincushion distortion where the top, bottom and sides appear to round inward. Most monitors offer controls to adjust these distortion types as well as trapezoid distortion, where the top and bottom edges are straight across and parallel to one another, but the side edges are straight but not parallel. If you don’t adjust these distortions, your image suffer accordingly.

Choosing the right monitor is essential for working long hours on the computer-riding internet or developing software. Following the above tips and technical jargons you are sure to find out a very eye-friendly monitor.

Cybersurfing with Amar Chandel
Instant text messages

AFTER Hotmail, Indians have earned quite a reputation for coming up with userfriendly software, solutions and services. Worthy of that trust is www.unimedia.net , a site maintained by Bangalore-based Graycell Applied Technologies Pvt Ltd. It allows users to send instant text messages to anyone across the world, whether or not he is logged on to the Net at that time or not. All that the recipient has to have is a receiving device like a pager or cell phone. Once you give the details of the device, a message is sent to it in an instant.

To make the service really global, the company has tied up with 95 service providers in 68 countries. So, you get mobility as well as mass usage at virtually no cost.

The company has had another first, a Net-based pager of the kind popularised worldwide by Yahoo. Sad that this service is not well known. One hopes the unimedia will get the attention that it deserves.

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Search engines have made the quest for information quite easy. But further refinements continue. In this regard, Copernic99 is quite a step forward. It targets your enquiries to some 30 engines like Yahoo, Excite, HotBot, Infoseek and Lycos and then stores and organises them for better search management and faster browsing.

Not only that, it gives relevancy score for each result and removes duplicates. The dead links are removed and documents downloaded for off-line browsing. You can specify the number of results you need (up to 300 per engine).

Similarly, it accesses popular e-mail directories to find people. Can be downloaded from www.copernic.com

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A new site, www.cameraview.com is specifically designed for photo equipment reviews. Professionals and amateurs can share reviews of cameras, lenses and other gear. You select the camera you want a review of and the search engine gets you comments on the camera, or any other piece of photographic equipment, including lenses, tripods, ballheads, digital cameras, film scanners etc. You can not only read the reviews done by others ; you can contribute your comments too.

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Here is a bit of comic relief that you can enjoy even without going on the Internet because it thrives on an aberration of Microsoft Office’97 itself. Type the sentence “I’d like the government to go”, highlight the sentence and ask the computer for a synonym (by clicking tools/language/thesaurus). The unexpected synonym you are offered is “Let’s drink to that”. Cheers to that!

Science Quiz
by J. P. Garg

1. Name the world’s fist test-tube baby. When and where was she born?

2. LLLT is a new technique in dentistry and is basically used to provide fast relief in dental pain. It also reduces the use of antibiotics. What does LLLT stand for?

3. What did Lewis Waterman of the USA and Lazlo Biro of Argentina invent in 1884 and 1944, respectively, which are commonly available in any stationary shop even in rural areas?

4. To know the location and study the movement and behaviour of a rare bird, scientists tie a collar with a small antenna around the neck of the bird and then leave it free. Which technical system is used for this purpose?

5. If you were a student of “ufology,” what would you be studying and researching?

6. When we observe the image of an object through a convex lens, the edges of the object may not appear sharp and may appear blurred and coloured. What is this defect of the image called and how is it usually removed?

7. In the event of a nuclear warfare, the sky would remain overcast with thick cover of dust and smoke for months and hardly any heat or light energy would reach the earth. What name has been given by the scientists to such a dreaded situation?

8. Unlike insects, which run away to save themselves during a forest fire, there are insects which not only detect heat and smoke from miles but also immediately fly towards the fire. Which are these insects?

9. Babbit “metal”, invented by the US inventor Isaac Babbit in 1839, is generally used for lining bearings of vehicles to reduce friction. What is it actually?

10. In his latest book “Seven Wonders of the Cosmos” the great Indian astronomer Jayant V. Narlikar has stated: “It was a wintry day in 1963 when I saw the sun rise in the west.” How was it possible? Which basic principle is applicable in this phenomenon?

ANSWERS

1. Luise Brown; 25th July, 1978; Oldham General Hospital, Lancashire (Great Britain) 2. Low level laser therapy 3. Fountain pen and ball-point pen 4. Radio transmitter — receiver system 5. Unidentified flying objects 6. Chromatic aberration; By using a suitable combination of a convex and a concave lens 7. Nuclear winter 8. Jewel beetles, also called fire beetles 9. An alloy of tin, antimony, copper and lead 10. By flying in a jet plane from east to west faster than the west-to-east motion.

Pint-size but real Dolby
There have been a lot of Virtual Dolby Digital TC-top speaker systems, but Altec Lansing’s ADA 105 is the first to provide five real speakers plus a subwoofer to produce the genuine article: 5.1 channels of Dolby Digital sound. The TV- top speaker bar houses two side-firing speakers delivering sound to the rear, while the unit’s front firing speakers create the left, right, and centre channles. Price $ 399. (Popular Science).

Shape-changing liquid lenses
Liquid lenses that can change their shape — and hence their magnification — at the flick of a switch have been developed by researchers in France.

The lenses could replace slow and bulky focusing mechanisms in a wide range of imaging devices such a endoscopes.

Development by Brauno Berge, a physicist at Joseph Fourier University in Grenoble, the simple lenses consist of a tiny drop of silicon oil suspended between two small volume of salty water in a cylindrical container, reports New Scientist.

The oil drop sits on a transparent polymer film and is kept in the centre by a hydrophilic coating around the edge of the film. The shape of the drop can be accurately changed in a few milliseconds by varying the voltage applied to the salty water on either side of the oil drop.

“Wired-up” fruit fly
Researchers at an agro-science centre in the United Kingdom are turning insects into living ‘biosensors’ which can warn when food starts getting spoiled.

The Scientists at the Institute of Arable Crops Research, Hertfordshire, have wired up the antennae of fruit flies to detect the first tiny odour of a rotting tomato.

The flies’ antennae are so sensitive that they can generate a signal from just one picogram of the substance, that is one million millionth of a gram.

The researchers hope the work will lead to super-efficient ways of monitoring food freshness using artificial sensors based on nature’s design, according to report in New Scientist.

Fruit flies, blow flies, bluebottles and carrion beetles all have a highly sensitive sense of smell operated through, nerve cells in their antennae. Some seeks out rotting food to eat, while others are looking for a place to lay their eggs.

The fly is held in place and its antennae wired up to an amplifier. The antennae have lots of different sensory hairs tuned to react to specific molecules. How they respond to smell and send signals to the brain is recorded.