|SCIENCE & TECHNOLOGY|
Any alternatives to polythene, plastics?
Conditional Access System
UNDERSTANDING THE UNIVERSE
Any alternatives to polythene, plastics?
IN today’s modern era of science and technology plastics have become one of the most widely used products all over the globe. The credit for this invention goes to the famous scientist Dr Alexander Parkes who had invented the first synthetic plastic i.e. celluloid way back in 1856.
Since then the number as well as the types and qualities have greatly increased, producing superior materials such as epoxies, polycarbonates, Teflon, and silicones. The bonding properties and chemical versatility of carbon account for the great number of plastics. Though we have been successful in creating such varieties, in the process, we have adversely affected the global eco-system as a whole. Today, plastics have created such a menace in many places that it has led to the proliferation in the spread of cancer by the production of deadly carcinogenic compounds. Polythene polution is not just an ugly sight in the hills, it has seriously damaged the environment by choking the soil. Thus the best alternative to plastics would be the use of biodegradable and naturally occurring products.
When we think of something as biodegradable we mean that it can be broken down and assimilated by natural means back into common earth elements like carbon and hydrogen. One such alternative is a biodegradable plastic eco-foam loose fill, which is comprised of over 99% cornstarch. Eco-foam loose fill with its soft resilient properties is very similar to polystyrene. But its most important advantage is that unlike polystyrene, eco-foam has no need for chemical blowing agents like CFCs, which harm the ozone layer. Besides, eco-foam starch based loose fill readily biodegrades in compost heaps, this providing a good source of manures. Also as it dissolves in water, you can sprinkle it on your lawn and the rainwater will wash it into the soil. More importantly, since it is made from corn and not from petroleum hydrocarbons, new stocks of raw materials can be grown each year. This would also ensure the minimal use of non-biodegradable resources.
Besides this, many western nations are using life science technologies to forge new links between agriculture and industry in creating renewable sustainable products. These new links, which are provided by a class of natural polymers known as PHAs allow photosynthesis to be harnessed directly to manufacture plastics, chemicals and coatings from plant crops and by fermentation. In this process, proprietary genes direct the metabolism of the plants and bacteria to these polymers, which accumulate as storage compounds, like starch and oils. After harvesting these PHA storage compounds may then be used directly plastics and coatings or converted into useful chemicals, meeting today’s environmental challenges.
Another very eco-friendly plastic is Green-sack film, which is, processed the same as conventional plastic and is available in several grades. Made from biodegradable polymers, Green-sack film starts life as kernel of grain and ends its life as compost, enriching the soil and completing the cycle.
Apart from these, there are other biodegradable plastics and polythene like Biopol made from renewable materials such as cottonseeds and cornstarch. These products are biodegradable in a normal composting process, yet they provide the functional characteristics of conventional plastics. All these biodegradable plastics are better than their conventional predecessors because they resist better to rain and bad weather and are transparent.
Over the past few years, an extensive effort has been made by scientists all around the globe in replacing non-biodegradable plastics with the biodegradable ones. In this connection, many professors and physicists like Prof Mrinal Bhattacharya of the University of Minnesota in the States are using proteins from cereal grains along with plant starch and degradable synthetic polymer to make this kind of a plastic. Starch based plastic act as a reacted blend of starch and synthic polymer. It is a renewable agricultural product and the use of this product will reduce the world’s dependence on oil — a non-renewable resource. Besides, they are recyclable and biodegradable thus reducing the environmental impact.
The recent invention of fibre extracted from feathers has shown significant results. It can replace more expensive plastic and fibreglass. The feather fibre is more absorbent than wood fibres. More importantly, it comes from any bird and commercial chickens.
Conditional Access System
CONDITIONAL Access System (CAS) has emerged as a technological empowerment and an entertainment revolution for the whole world. The cable operators require a system for ensuring that the timely payment is received for the programme content they deliver to the customer. The technical system that implements this objective is the Conditional Access System. Viewers will get to choose the channels they want and pay only for those. Moreover, the viewer gets to receive all the free to air channels at a rate fixed by the government. The entire system shall become more transparent.
A conditional access (CA) system is enabled through the process of "scrambling" and "encryption" to prevent unauthorised reception. Scrambling makes the sound, pictures and data unintelligible. Encryption enables the secret keys to be transmitted with the scrambled signal in order to pave the way for a descrambler to work.
The digitised broadcast signal is applied to the scrambler. It incorporates an algorithm to prevent unauthorised attack. The output of the scrambler is applied to the distribution media like cable, satellite or terresterial, for delivery to the subscriber. The CAS system generates the control word (CW) for the scrambler and also generates Entitlement Control Messages (ECMs). These are needed to recover the CW at the descrambling end. Conditional access system also stores smart card information in the form of a database. This is known as a Subscriber Management System (SMS). The SMS contains a database of all the paid subscribers. The services offered are pay per view (PPV), impulse pay per view (IPPV), Video on demand (VOD) and near video on demand (NVOD). CAS will make it mandatory for the pay channels to be compulsorily routed through a settop box (STB). The cost of the analog box shall be around Rs 2000 and that of digital one will be Rs 2600. The government has ensured that free-to-air (FTA) channel prices remain at maximum of Rs 72 plus taxes for a minimum of 30 channels. While this is a law, the government has informally convinced cable operators to deliver up to 70 FTA channels.
The viewers who are unable to afford the STB can rent it. INCableNet has launched a scheme in which digital STBs will be available to the customers at a refundable deposit of Rs 999 and a daily rent of Re 1. Siticable and Hathway too are making available STBs on similar schemes.
Analogue set-top box (STB) will enable a viewer to choose for the pay channels and the digital box will deliver value added services like pay-per-view and Internet enabling. Analogue box cannot be upgraded whereas the digital box can be upgraded through software downloads.
In the case of digital STB the cable operator can know the channel that the viewer watching which is not possible in analogue STB. One box will not work for all TVs in the home and an additional one shall be required for the second TV.
The Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis of the Conditional access system (CAS) yields interesting results. The major strength is that the viewer can choose the channel and pay for it. The programme content will improve owing to competition. Several pay channels may switch to free to air channels to attain the desired reach. The entire system will get more transparent and the government will get more revenue. The weaknesses include the lack of awareness on CAS amongst the masses.
Cost of switching to CAS can be expensive. The maximum tariff of Rs 72 for free to air channel may reduce the service quality. Small cable operators may close down, leading to monopoly in cable distribution segment. Cable viewers may end up paying more for less viewing. The major opportunities exist for the production houses to develop competencies in specific type of programmes to cater to a particular audience. Focused advertisements can reach the right audience. The CAS equipment manufacturers can expand their business.
DTH and the terrestrial
Doordarshan are the biggest threats to CAS cable TV viewership. The
cost of set-up boxes can be a nightmare for the cable operator and the
viewer. Due to the drop in advertisement revenue, the Broadcasters
might hike the subscription charges and eventually pass on the
increased costs in the form of inflated bills to the consumer.
Ultimately, it is the end user who has to bear the brunt.
UNDERSTANDING THE UNIVERSE
The light given by fluorescent tubes and mercury and sodium vapour lamps is different from that produced by a filament lamp. Please explain why it is so.
Filament lamp was the first one to be invented and is still in wide use. It depends on heating a filament of high resistance wire by passing a current through it. When the temperature is high enough the light becomes yellowish and then whitish. The filament is enclosed in an inert atmosphere to make it last long. Production of lot of heat is a necessary outcome of a high wattage filament bulb. All the other types of lights you have mentioned are in the nature of discharge tubes in which different gases are ionised. For starting all of them need a source of electrons. Some sort of a filament usually provides this. They also need a starter. This gives a pulse of high voltage to start a discharge in the low-pressure vapour inside the tube. Once the discharge is started the gas inside becomes a conducting plasma and the initial spurt in voltage is not required. Till a few years ago the starters were chokes and condensers. Now we have quieter electronic starters. All the modern lights need the start of such a plasma discharge. In the case of fluorescent lights one uses the predominantly ultraviolet emission in a mercury vapour discharge to impinge on a fluorescent material coated on the inner surface of the tube. This is also true of the so-called long duration modern lamps. The light colour given out depends on the kind of fluorescent material used.
For the sodium vapour lamps one uses sodium vapour whose predominant emission at moderate temperature is in the yellow. The wavelength or the colour of the emission depends on the atomic energy levels of the atoms of the material used. Neon filled tubes, for example, give out red light. Incidentally, I suspect that somewhat gradual coming on of a sodium lamp may due to the fact that it might take a little time to produce enough vapour starting from a cold start.
I would warn you that I am not a specialist in this area. My arguments are based on a guess about the essential physics that might be involved. I have warned you earlier too that I am not in the business of delivering the truth but in exposing how I think about a problem.
Tides occur only in seas and oceans but not in rivers, canals and lakes. Why is it so?
Tides are produced because the gravitational attraction of the moon on the near side of the earth is greater than on the far side. This differential attraction across the earth results in a bulge in the oceans on both sides of the moon earth line. The force difference is not confined to the oceans but it becomes spectacularly visible in oceans and large seas because the rise of water is compensated by the inflow from other places far from the moon earth line. It is not visible in rivers, lakes and canals, because nothing can flow in to them from far away to fill the void that would be created if the water were to rise up. One knows that the height of the tide in seas is also not the same. It is again influenced by the ease or difficulty with which water can flow in and out.
While we are talking of tidal
phenomena it might be worth pointing out that this has been responsible for the
fact that the rotation of the moon around its axis and the period of its
revolution around the earth got synchronised resulting in the fact that from
the earth we can see only one face of the moon. For seeing the backside of the
moon we had to wait till arrival of the space age when spacecraft could be sent
out to take its images.
NEW products & discoveries
Beyond solar system
On the interplanetary highway, there are no mile markers and no exit signs. Precious few clues indicate that you’re nearing the edge of the solar system. Those clues, however, are revealing that the venerable Voyager 1 spacecraft, launched 26 years ago and now 90 times as far from the sun as Earth is, either has reached or will soon enter a turbulent region near the solar system’s final frontier. There, the solar wind first slams into large numbers of atoms and molecules that have leaked into the solar system from interstellar space. The encounter puts the brakes on the solar wind, causing it to abruptly slow from supersonic speeds of 400 to 700 kilometers per second down to subsonic speeds of 100 km/sec, according to simulations.
Signals that the elderly spacecraft recently radioed to Earth indicate that it might have already encountered this bizarre region, known as the termination shock. If so, it would be the first time that a human-made object has reached that milestone, notes Stamatios (Tom) Krimigis of the John Hopkins Applied Physics Laboratory in Laurel, Md. The craft would then be on course to exit the solar system.
University of Melbourne physicists have helped discover a new state of matter that may shed light on the fabric of the universe.
The university team of 14 is part of a group of 300 physicists from 13 countries known as the "Belle collaboration". They have discovered a sub-atomic particle that they are having difficulty explaining and difficulty fitting with any current theory that attempts to describe matter.
Their research will be published in Physical Review Letters (in press).
"It could mean some of the standard and accepted theories on matter will need to be modified to incorporate some new physics," says University of Melbourne doctoral student in physics and Belle team member, Mr Craig Everton.
The sub-atomic particle they believe could be a meson. A meson by itself is a relatively obscure particle, but one which is made up of quarks, the basic building blocks of not just life, but everything that exists in this universe - as we know it.