light pollution essay "cause,effects,reductions"

                             what is light pollution?

Light pollution occurs when artificial light intrudes on the nighttime setting. This phenomenon is pronounced around urban centers, where city lights diminish the view of stars and planets. A satellite view at night shows light pollution as glowing regions around urban areas. In addition to brightened skies around cities, light pollution also refers to any outdoor light that creates glare and interferes with the natural night environment. The National Park Service refers to a single source of light that intrudes on the night as "light trespass." 

Cause

Light pollution results from outdoor lights aimed upward or sideways --- the light scatters in the atmosphere and reflects back to the ground. The result is sky glow. Particles in the atmosphere responsible for air pollution accentuate light pollution by increasing the amount of light scatter. According to the International Dark-Sky Association, light sources that emit blue light are particularly disruptive to night skies due to greater light scattering. 

Effects

According to the National Park Service, city lights as far as 200 miles away diminish views of night skies. Light pollution is a major concern for observatories as lights from urban areas compete with lights from stars and planets, reducing visibility of the objects that observatories study. This type of pollution also affects wildlife and plants. Night lights disorient hatching sea turtles, migrating birds and nocturnal animals. Lights attract insects, which may in turn interfere with pollination of nocturnal flowers. In humans, light pollution can interfere with natural circadian rhythms by preventing the production of melatonin, the chemical that regulates sleep patterns. Low melatonin levels have been linked to increased cancer risks.

Reduction

There are ways to reduce light pollution, starting in your own neighborhood. Make sure outdoor lights reflect downward in what are called fully-shielded fixtures. Also consider exchanging high-wattage bulbs for dimmer ones and selecting warm-white lights with low emission of blue light. A great way to save energy and reduce trespassing light is to turn off outdoor lights unless needed.

Difference Between Cosmos and Universe

Difference Between Cosmos and Universe

Cosmos vs Universe

The world that we live in is very vast and boundless. While the human race is confined and live in a small portion of the world, people are aware of the existence of other planets and galaxies as well as many other things in the universe and the cosmos.

“Cosmos” is defined as a harmonious and orderly whole, a system that is governed not by human or supernatural laws but by natural law. It is used to refer to objects that exist naturally especially those that can be seen in the sky. The term “cosmos” has two connotations. It comes from the Greek word “kosmos” which means “order, good order,” or “orderly arrangement” from which the verb “kosmein” which means “arrange” or “adorn” is derived and passed on to the English language.

It was first used by Pythagoras, a 6th century Greek philosopher, mathematician (he discovered the Pythagorean Theorem), and founder of the religious movement Pythagoreanism to refer to the whole physical world or the universe.

“Universe” is defined as “everything that exists including all matter and energy, the Earth, and everything in it together with extraterrestrial or celestial bodies such as the galaxies, stars, meteors, and everything that can be found in intergalactic space.” It is everything that existed, that is existing, and will exist. It has three elements, namely; space and time or the vacuum, matter and energy that occupy space and time, and the physical laws that govern them which have been constant throughout its history.

The concept of the universe was first developed by the Ancient Greeks. The term “universe” comes from the Latin word “universus” which means “whole, entire, all together, or turned into one” which was first used by Cicero. It entered the English language through the Old French “univers” which means “the whole world” which was in turn based on the Greek word “holos” which means “whole.” It appeared in the English language in 1589 in Puttenham’s work “The Arte of English Poesie” but was first used in 1385 in Chaucer’s poem “Troilus and Criseyde.”

The words “cosmos” and “universe” are used synonymously as they refer to the same concept which is the world or nature. “Universe” seems to have a narrower or smaller scope than “cosmos,” though, and “cosmos” signifies a larger and more complex system.

Summary:

1.“Cosmos” is a whole harmonious and orderly system that is governed by natural law while “universe” is everything that exists including time and space, matter, and the laws that govern them.

2.The word “cosmos” comes from the Greek word “kosmos” which means “order or orderly arrangement” while the word “universe” comes from the Latin word “universus” which means “whole or entire,” also from the Greek “holos” which also means “whole.”

3.The word “cosmos” was first used by the Greek philosopher and mathematician Pythagoras while the word “universe” was first used by the Roman philosopher, theorist, and statesman Cicero.

4.“Universe” may connote a much smaller scope while “cosmos” implies a larger scope.

How do online booking system works?

          

How do online booking system works?

The online system you see may link to a number of other systems.   For instance, most airline reservations are made via the API provided by one of the GDS (Galileo, Sabre, Amadeus etc).   They, in turn, connect to the airlines through long establised communications system the oldest of which is computerised telex messages.   The website may cache some response from the GDS and use them to offer fares, only going to the GDS when the passenger says "yes".   The GDS may also have cached some answers.   The result can be that the website offers a fare and the airline says "no".   Add to that the fact that some of the actual fares are stored in a system operated by the agency which means the agency system has to go there, determine if they have a "special fare" then go to the GDS and they go on to the airline to determine availability and it all gets messy.

Some hotels and cars are also served by the GDS.   However, with hotels (and a lesser exten cars) there are some wholesalers in the mix as well.   They negotiate rates with the hotels, add their own markup and sell direct to the public but they also offer rates via third parties at rates which may not be the same as the rates on their website.   The ultimate seller probably adds his own markup so you need to factor that calculation in.   All of this is done via APIs (or an earlier version an XML message set).   Of course, one website may be connecting to a GDS for some hotels, a wholesaler for others direct to an hotel (group) for others.

Once you've got someone hooked in to make a booking you need some kind of storage to record what they've done and connection to at least one payment gateway to collect money from credit/debit cards.   In some countries there may also be ways of paying - at least one Asian market allows people to make a booking and then go to an ATM to pay.   In all those cases you need to be able to manage what happens if the payment fails.

Then you have to consider, changes made by both the passenger and the vendor (e.g. schedule changes), refunds, complaints etc.   It's also the case that different websites have different business mixes.   Theatres, concerts, railways, long distance buses, ferries, cruises, all inclusive package holidays and festivals to name but a few all of which have different detailed methodologies.