Monday, April 30, 2007

Postal Marking

A postage stamp is proof of pre-paying a fee for postal services. Usually a small paper rectangle which is attached to an envelope, signifying that the person sending the letter or package has paid for delivery; it is the most popular option to using a prepaid-postage envelope.


In it he argued that it would be well again for the sender to pay the cost of delivery, rather than the addressee who could refuse the letter if they could not or did not want to pay, as occasionally happened at the time. He also argued for a identical rate of one penny per letter, no matter where its end. Accounting costs for the government would thus be cut; postage would no longer be charged according to how far a letter had traveled, which necessary each letter to have an individual entry in the Royal Mail's accounts. Chalmers' ideas were finally adopted by Parliament in August, 1839 and the General Post Office launched the Penny Post service the next year in 1840 with two prepaid-postage symbolic envelopes or wrappers: one valued at a penny and one valued at two pence.

Tuesday, April 24, 2007

Brown Thrasher

The Brown Thrasher is a common type of thrasher, part of a family of New World birds that includes New World catbirds and mockingbirds.The Brown Thrasher is, as the name suggests, mostly brown or reddish-brown on top of, with a white breast and throat streaked with brown, and two white bars on each wing. It has a long tail, and its beak is also relatively large and somewhat curved. Adults average about 29 cm (11.5 in) in length.
It is difficult to see all this however, as the bird is a retiring type that prefers thickets and heavy brush, often searching for food in dry leaves on the ground. In fact, it is more probable to be heard than seen, not only because of the rattling of leaves, but also because of its call, a sharp lip-smacking type sound. This bird is omnivorous, eating insects, berries, nuts and seeds, as well as earthworms, snails and sometimes lizards.Its breeding variety includes the United States and Canada east of the Rocky Mountains. It is a partial migrant, with northern birds wintering in the southern USA, where it occurs all through the year. There is a single British record of this unlikely transatlantic vagrant.
The female lays 3 to 5 eggs in a twiggy nest lined with grass. The nest is built in a dense shrub or low in a tree. Both parents incubate and feed the young. These birds raise two, rarely three, broods in a year. The male sings a series of short recurring melodious phrases from an open perch to defend his territory and is also very aggressive in defending the nest.
Although this bird is widespread and still common, it has declined in numbers in some areas due to loss of suitable habitat.
The Brown Thrasher is the official state bird of Georgia, and the inspiration for the name of Atlanta's National Hockey League team, the Atlanta Thrashers.

Wednesday, April 18, 2007

Delta Air Lines

Delta Air is a major U.S. airline headquartered in Atlanta, Georgia, operating a large domestic and international network that spans North America, South America, Europe, Asia, and the Caribbean.

Delta operates hubs at Atlanta, Cincinnati, New York-JFK, and Salt Lake City. Delta also has great operations in many other cities, including Boston, Columbus, Fort Lauderdale, Los Angeles, New York-LaGuardia, Orlando, and Washington-Reagan. Delta is also the foremost hauler in Florida. Its key worldwide gateways are Atlanta, Cincinnati, and New York-JFK.

In terms of passengers approved, Delta is the second-largest airline in the world. In terms of total operating revenues, Delta is the fourth-largest airline in the world As of September 1, 2005, Delta served 178 domestic cities in 46 states, Puerto Rico, and the U.S. Virgin Islands, as well as 71 international cities, including 10 future ones, in 45 countries.

Early history

Delta timetable from 1934
Delta Boeing 747, operated by Pan Am, at London Heathrow Airport in May 1974.The corporation has its roots in Huff Daland Dusters, which was founded in 1924 in Macon, Georgia by more than a few partners with Collett E. Woolman becoming the world's first aerial crop dusting company. Huff Daland moved to Monroe, Louisiana the following year. In 1928, Huff Daland Dusters was purchased by C.E. Woolman and renamed Delta Air military after the Mississippi Delta, where its route joined Dallas, Texas to Jackson, Mississippi, via Shreveport, Louisiana and Monroe. By 1934, Delta Air began mail service from Charleston to Fort Worth, including Atlanta, Augusta and other stops in Georgia.

In 1941, Delta enthused its headquarters from Monroe to Atlanta, Georgia, to center itself along its new way network that joined Chicago and New Orleans to Florida and Ohio which would later become a Delta hub. In the 1950s, Delta began flights from New Orleans to the Caribbean and Venezuela, becoming the number 2 U.S. carrier in the region after Pan Am and Braniff. On May 1, 1953, Delta combined with Chicago and Southern to enlarge routes in Midwest. In 1955 Delta introduced the "hub and spoke system" where flights are running scared to a central point then sent out to other cities. By the early 1960s, Delta's route network extended to the West Coast, and Dallas was emerging as its second hub city.

Tuesday, April 10, 2007

Transistor radio

The transistor radio is a small radio receiver.
RCA demonstrated a prototype transistor radio in 1952. The first commercial transistor radio, the Regency TR-1, was announced on October 18, 1954 by the Regency Division of Industrial Development Engineering Associates of Indianapolis, Indiana and put on sale in November of 1954. It cost $49.95 (the equivalent of $361 in year-2005 dollars) and sold approximately 100,000 units.
The use of transistors in its place of vacuum tubes as the amplifier elements meant that the device was much smaller and necessary far less power to operate than a tubed radio. The characteristic portable radio of the fifties was about the size and weight of a small laptop computer, and contained several heavy batteries: one or more A batteries to heat the tube filaments and a large 45 to 90 volt B battery for plate voltage. By comparison, the "transistor" was about the size and weight of today's cassette-playing Walkman and operated off a single compact 9 V battery. The now-familiar 9 V battery was introduced particularly for powering transistor radios.

Friday, April 06, 2007


The transistor is a solid state semiconductor device which can be used for amplification, switching, voltage stabilization, signal modulation and many other functions. It acts as a changeable valve which, based on its input current (BJT) or input voltage (FET), allows a precise amount of current to flow through it from the circuit's voltage supply.In essence, a transistor has three terminals. A current or voltage applied through/across two terminals controls a larger current through the other terminal and the common terminal. In analog circuits, transistors are used in amplifiers. Analog circuits include audio amplifiers, stabilised power supplies and radio frequency amplifiers. In digital circuits, transistors function basically as electrical switches. Digital circuits include logic gates, RAM (random access memory) and microprocessors.Transistor was also the common name in the sixties for a transistor radio, a portable radio that used transistors (rather than vacuum tubes) as its active electronic components. This is still one of the dictionary definitions of transistor.

Monday, April 02, 2007

Traffic psychology

Traffic psychology is a young increasing field in psychology. Whereas traffic psychology is first and foremost related to "the study of the behaviour of road users and the psychological processes underlying that behaviour" as well as to the relation between behaviour and accidents, transportation psychology, sometimes referred to as mobility psychology, has its focus on mobility issues, individual and social factors in the movement of people and goods, and travel demand management (TDM).
There is no single theoretical framework in traffic psychology, but many specific models explaining, e.g., perceptual, attentional, cognitive, social, motivational and emotional determinants of mobility and traffic behaviour. One of the most famous behavioural models divides the various tasks concerned in traffic participation into three hierarchical levels, i.e. the strategic, the tactical and the operational level. The model demonstrates the diversity of decision and control tasks which have to be accomplished when driving a vehicle. However, until now, most of the psychological models have a rather heuristic nature, e.g. risk theories like the risk compensation hypothesis, Fuller's task capability model, and thus are not adequately precise to allow for concrete behavioural prediction and control. This is partly due to the importance of individual differences, a major topic of psychology which in traffic and transportation has not yet been adequately accounted for. On the other hand, social-psychological attitude-behaviour models, such as Ajzen's theory of planned behavior, have been helpful in identifying determinants of mobility decisions.