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Wednesday, 21 June 2017

Radish

RADISHES IN HISTORY

The ancient Egyptians are known to have cultivated radishes since 2700 BC at least.


When the Ancient Egyptians were building the pyramids, they paid the workers in radishes.

The Ancient Greeks revered radishes and made gold replicas of them to be offered to the god Apollo.

The ancient Roman writer Pliny described the radish as "a vulgar article of the diet...with a remarkable power of causing flatulence."

RADISHES IN LITERATURE

Beatrix Potter’s Peter Rabbit enjoyed radishes. His favorite was a rather long variety called Long Scarlet.



In the novel Gone with the Wind, Scarlett O'Hara said: "As God is my witness, I'll never be hungry again," after eating a radish.

FUN RADISH FACTS

Varieties of radish include Bunny Tail, French Breakfast, Plum Purple and Sicily Giant.

The weight of radishes sold in the UK in 2012 was more than the weight of the Eiffel Tower.

The Mexican town of Oaxaca has a festival called Noche de rabanos (Night of the radishes) on December 23rd every year. It features a number of radish-themed events including radish carving.The radish carving competition has been held in Oaxaca every year since 1897.

Dulces Tradicionales Oaxaqueños entry at the 2014 Night of the Radishes

The centrepiece of Noche de rabanos is an exhibition of radish carvings usually including a Nativity scene carved out of radishes.

Sources Daily Express, Food For Thought by Ed Pearce

Tuesday, 20 June 2017

Radioactivity

Radiation is the emission of radiant energy as particles, waves, sound etc. Radioactivity is the spontaneous emission of radiation from the nucleus of atoms of certain substances, termed radioactive.

HISTORY

While experimenting with high voltages applied to an evacuated tube on November 8, 1895, German scientist Wilhelm Röntgen noticed a fluorescence on a nearby plate of coated glass. Within a month, he discovered that the radiation causing this was able to pass through everyday materials such as paper, wood and living tissue and it produced an image on photographic plates as well as a fluorescent screen. Röntgen could not determine how the radiation was carried through space or why it had such penetrating power. For this reason he called this type of radiation X rays.

First medical X-ray by Wilhelm Röntgen of his wife Anna Bertha Ludwig's hand

On March 1, 1896 French physicist Henri Becquerel discovered the principle of radioactive decay when he exposed photographic plates to uranium.

Becqurel's doctoral student, Marie Curie, discovered that only certain chemical elements gave off these rays of energy. She named this behavior radioactivity.

Hearing of Becquerel's experience with uranium, the New Zealand physicist Ernest Rutherford started to explore its radioactivity. He found through simple experimentation two different ways in which these particles penetrate matter. In 1899 he coined the the two distinct types of radiation that he'd found alpha ray and beta ray. Alpha rays had short penetration (it was stopped by paper) and a positive charge and beta rays were more penetrating (able to expose film through paper but not metal) and had a negative charge,

Ernest Rutherford at the McGill University in 1905

In 1900, the French scientist Paul Villard discovered a third neutrally charged and especially penetrating type of radiation from radium, and after he described it, Rutherford realized it must be yet a third type of radiation, which in 1903 he named gamma rays.

All three of Rutherford's terms are in standard use today – other types of radioactive decay have since been discovered, but Rutherford's three types are among the most common.

Marie Curie was awarded the Nobel Prize for physics in 1903 as a result of her work on radioactivity. However Marie and her husband, Pierre, had exposed themselves to massive doses of radiation poisoning. They had failed to see that radioactivity might be dangerous and ascribed their increasing fatigue, weight loss, aches and pains to overwork. It was not only the Curies who believed radiation to be harmless, many physicians used it as a treatment for a variety of ailments including minor ones such as acne and ringworm.

Pierre and Marie Curie in the laboratory

On August 6, 1945, Hiroshima doctors figured out what kind of bomb had been dropped when their x-ray film was exposed by the radiation.

Hibakusha, survivors of the atomic bombs, faced considerable discrimination in Japan following the war. Families forbade their children from marrying hibakusha, and they were often denied employment due to fears that the radiation they were exposed to was hereditary, or contagious.

In 1956, the actress Susan Hayward (1917-1975) starred with John Wayne in The Conqueror. The movie was filmed near a U.S. atomic bomb test site, radiation from which was probably the cause of her fatal brain cancer. By the end of 1980, 46 members of the film’s cast and crew had died from some form of the disease, including Wayne.

The Fukushima Daiichi Nuclear Power Plant suffered major damage from the magnitude 9.0 earthquake and tsunami that hit Japan on March 11, 2011. After the disaster, the radiation levels at were so high that the robots sent to remove the plant's melted fuel rods died.

FUN RADIOACTIVITY FACTS

Marie Curie's notebooks are still radioactive.

Full-body CT scans expose people to similar levels of radiation as the atomic bombs used in Hiroshima.


Gamma rays from space are the most energetic releases of energy known, even more energetic than supernovas.

On average, half of all false teeth have some form of radioactivity.

Fly ash emitted by a coal power plant carries  one hundred times more radiation into the surrounding environment than a nuclear power plant producing the same amount of energy.

All glossy magazines are radioactive.

Carrot juice is ten times more radioactive than beer.

Monday, 19 June 2017

Radio receiver

Early developments in radio were called 'wireless telegraphy', which is why the radio used to be called the wireless.

Family listening to the first broadcasts around 1920 with a crystal receiver. The mom and dad share an earphone

President Warren Harding had the first radio installed in the White House on February 8 1922.

The UK government introduced a radio licence costing 10 shillings (50p) in 1922. Until 1971 British citizens could not officially listen to the radio in the UK without having a licence.

In 1923 a great improvement in radio receivers was advertised. The new models had a concealed speaker and eliminated the need for headphones, which were considered a nuisance because they were so heavy to wear.

By the mid-1920s, home radio receivers were becoming ubiquitous. Every home had one. Dance Bands broadcasting from Hotels and Dance Halls became a prominent feature of radio station programming.

In 1925 E. S. Ted Rogers Sr of Toronto, Canada. invented the alternating-current tube, making possible electric radios with no batteries. "All-electric" receiving sets started appearing the following year.


In 1929, American Paul Galvin, the head of Galvin Manufacturing Corporation, invented the first car radio. Consumers had to purchase the radios separately as they were not available from automobile manufacturers. Galvin coined the name Motorola for the company's new products, combining the idea of motion and radio.

The Regency TR-1 transistor radio was announced on October 18, 1954. Two companies working together, Texas Instruments of Dallas, Texas and Industrial Development Engineering Associates (I.D.E.A.) of Indianapolis, Indiana, were behind its unveiling. The Regency TR-1 was put on sale in November 1954, and was the first practical transistor radio made in any significant numbers.

Regency TR-1 transistor radio

In 1991, the British inventor Trevor Baylis saw a television program about AIDS in Africa. He was horrified by reports from the dark continent that safe-sex education wasn't getting through, but intrigued that one way to stop the spread of AIDS was for people to hear educational information on the radio. So Baylis devised a contraption that didn't need batteries and ran off an internal generator powered by a mainspring wound by a hand crank. After Baylis demonstrated his wind-up radio to Nelson Mandela, it was distributed all over Africa.

Radio broadcasting

The word 'broadcasting', referring to radio transmissions, was originally an agricultural term for the wide scattering of seeds.

In 1906 American inventor Lee de Forest invented the three-element "Audion" (triode) vacuum tube, the first practical amplification device. The tube represented the foundation of the field of electronics, making possible radio broadcasting.

The first public radio broadcast took place on January 13, 1910 when De Forest transmitted the voices of Metropolitan Opera stars to several receivers in New York City.

Six weeks later, on February 24, 1910, the Manhattan Opera Company's Mme. Mariette Mazarin sang "La Habanera" from Carmen over a transmitter located in De Forest's laboratory.

February 24, 1910 radio broadcast by Mme. Mariette Mazarin of the Manhattan Opera Company

De Forest's test broadcasts showed that the idea was not yet technically feasible, and the inventor would not make any additional entertainment broadcasts until late 1916, when more capable vacuum-tube equipment became available.

Following the development of vacuum-tube transmitters that made audio transmissions possible, the first spoken-word election night broadcast was made on November 7, 1916 by the DeForest Radio Telephone and Telegraph Company's station, 2XG, located in the Highbridge section of New York City. The broadcast announced the results of the presidential election between President Woodrow Wilson, the Democratic candidate, and Supreme Court Justice Charles Evans Hughes, the Republican candidate.

Lee DeForest broadcasting Columbia phonograph records

During the 1910s, the only listeners to voice radio were a few engineers and hobbyists called hams. The equipment was cumbersome and required a fair amount of technical knowledge. After World War I, technological advances brought more appliances into the home and radio companies formed to build and sell ready-made machines.

Montreal, Quebec radio station XWA, Canada's first and oldest broadcasting station, began test transmissions in 1919. Their first documented entertainment broadcast was made on the evening of May 20, 1920 when a concert was prepared for a Royal Society of Canada audience listening 110 miles (175 kilometres) away at the Château Laurier in the city of Ottawa.

At the time these broadcasts received little publicity beyond a few local newspaper reports, in contrast to a similar broadcast made on June 15, 1920 by the Marconi station at Chelmsford in Essex, England featuring the famous soprano Dame Nellie Melba, which garnered broad international attention.

In 1920, Westinghouse Corporation, one of USA's leading radio manufacturers, had an idea for selling more of their products: It would offer programming. They built the first radio station, KDKA in Pittsburgh, which started broadcasting on the evening of November 2, 1920, with a transmission of the returns of the Harding-Cox presidential election.


On January 2, 1921 KDKA aired the first religious service in the history of radio. It was undertaken by Westinghouse to test its ability to do a remote broadcast far from a radio studio. Pittsburgh's Calvary Episcopal Church was chosen because one of the Westinghouse engineers was a member of the choir and was able to make the arrangements. KDKA soon offered a regular Sunday evening service from Calvary Episcopal Church.

KDKA was a huge success, inspiring other companies to take up broadcasting. Within four years there were 600 commercial stations around the US.

Circa 1921 photograph of the 9th floor KDKA transmission room.

While serving in the United States Army Signal Corps during World War I, electrical engineer Edwin H Armstrong invented the superheterodyne circuit. This is a highly selective means of receiving, converting, and greatly amplifying a wide spectrum of very weak, high-frequency electromagnetic waves. It laid the foundation for the success of radio broadcasting.

In 1933, Armstrong brought about an even more revolutionary change in the broadcasting business when he secured the circuit patents that were the basis of the frequency modulation (FM) system. He gave the first public demonstration of FM broadcasting in the United States at Alpine, New Jersey in 1935.

Commercial FM broadcasting began in 1941 in the U.S. when Nashville station W47NV started operations. W47NV was the first commercial FM radio station to receive a license, some 20 years after its AM radio counterpart, KDKA in Pittsburgh.

W47NV operated with 20,000 watts on a frequency of 44,700 kilocycles.

The world's first all-sports radio station, American radio station WFAN, was launched in New York City in 1987 as the world's first all-sports radio station.

Norway was the first country in the world to start phasing out the FM radio signal in favour of Digital Audio Broadcasting (DAB). It started turning off FM radio on January 11, 2017 in the northernmost city of Bodø.

Source Christianity.com

Radio

Radio is the transmission and reception of radio waves. When radio signals are sent out to many receivers at the same time, it is called a broadcast.

The first person to theorize the existence of radio waves was the Scottish physicist James Clerk Maxwell. His studies of light led him to the electromagnetic theory and in 1865 he proved that radio waves are possible.

The German scientist Heinrich Rudolf Hertz discovered the use of radio waves in transmitting information in the mid 1880s. However, with an uncharacteristic lack of foresight, while demonstrating electromagnetic waves in 1888, Hertz told his students, "I don't see any useful purpose for this mysterious, invisible electromagnetic energy."

Fortunately, others saw the potential in the technology and by 1890, French physicist Édouard Branley had found a way to convert incoming signals to direct current, an important development in radio reception.


Russian scientist Alexander Stepanovich Popov demonstrated to the Russian Physical and Chemical Societyin St Petersburg in 1895 his invention, the Popov lightning detector — a primitive radio receiver. In some parts of the former Soviet Union the anniversary of this day is celebrated as Radio Day.

In 1893 the Serbian-American inventor,  Nikola Tesla gave the first public demonstration of radio in St. Louis, Missouri. Five years later, at the Electrical Exhibition held at Madison Square Garden, Nikola Tesla successfully demonstrated a radio-controlled boat. He was awarded U.S. patent No. 613,809 for a "Method of and Apparatus for Controlling Mechanism of Moving Vessels or Vehicles."

Italian inventor and electrical engineer. Gugielmo Marconi first began pursuing the idea of building a wireless telegraphy system based on Hertzian waves (radio) at his father's Italian country estate in 1895. Marconi gained a patent on the system the following year and in 1897 he formed in England Marconi's Wireless Telegraph Company Ltd.

British Post Office engineers inspect Marconi's radio equipment  1897. Cardiff Council Flat Holm Project. 

In 1901, Guglielmo Marconi combined the equipment of Hertz and Branley to transmit a radio signal across the Atlantic. Marconi’s pioneering development of long-distance wireless telegraphy has led to him being widely regarded as the inventor of the radio.

The term "radio" is derived from the Latin word "radius", meaning "spoke of a wheel, beam of light, ray". Although Hertz discovered the use of radio waves in transmitting information in 1886, the regular use of "radio" as a standalone word dates back to only December 30, 1904, when instructions issued by the British Post Office for transmitting telegrams specified that "The word 'Radio'... is sent in the Service Instructions." Before that, such transmissions were always referred to as “wireless telegraphy”.

Early radio messages were sent in Morse code because voice transmission required more power and better signal control than were available at the time.

The first human voice to be transmitted by radio is generally accepted to be that of Quebec physicist Reginald Aubrey Fessenden. In 1903 he built his first high-frequency alternator, drawing on the unsuccessful work of Tesla during the 1890s.

Reginald Fessenden

In 1906 Fessenden built his second alternator, which was capable of 80000 cycles. He gave the world’s first public demonstration of “true” radiotelephony broadcasting on December 21, 1906 at Brant Rock, Massachusetts. It operated in “LF” spectrum at 50 kHz with a wavelength of 6,000 meters, or 19,680 feet (about 3.75 miles). As part of the demonstration, speech was transmitted 18 kilometers (11 miles) to a listening site at Plymouth, Massachusetts. This led to the broadcasting of news, music and entertainment that we have today.

Many of today's history books and websites credit Fessenden with broadcasting music, poetry and a scripture reading to ships on the Atlantic from Brant Rock on Christmas Eve, 1906. However, validation of this event (the one solitary account was provided by Fessenden himself more than 25 years after the fact) has never been satisfactorily accomplished

In the early years of commercial broadcasting in the 1920s, Amplitude Modulation, usually shortened to AM, was the only kind of radio widely used. AM is a simple way to send a radio signal. The signal can travel long distances, and appear in faraway places, because of the earth's ionosphere. In 1933 American electrical engineer and inventor, Edwin Armstrong introduced frequency modulation (FM), a static-free version of radio.  He was granted five U.S. patents covering the basic features of the new system on December 26, 1933.

When transmitting analogue sound, the sound quality of FM signals is better than that of AM signals. However, FM signals do not travel as far as AM because they use higher frequencies that do not bounce off the Kennelly–Heaviside layer.

FM radio was demonstrated to the Federal Communications Commission for the first time in 1940. Today, many radio stations send out both kinds of signals. AM may be used for talk shows, and FM for music.

A Fisher 500 AM/FM hi-fi receiver from 1959.

Since 2012, February 13 has been celebrated by Unesco as World Radio Day. The date was chosen as United Nations Radio was launched on February 13, 1946.

Sources Daily Express, The Independent, Europress Encyclopedia

Sunday, 18 June 2017

Radar

Radar is a machine that uses radio waves for echolocation to detect objects such as aircraft, spacecraft, ships, guided missiles, motor vehicles, weather formations, and terrain.

Long-range radar antenna, used to track space objects and ballistic missiles.

The direction of an object is ascertained by transmitting a beam of short-wavelength short-pulse radio waves, and picking up the reflected beam. Distance is determined by timing the journey of the radio waves (traveling at the speed of light) to the object and back again.

In 1886, German physicist Heinrich Hertz was the first to show that radio waves could be reflected from solid objects.

The German inventor Christian Hülsmeyer was the first to use radio waves to detect the presence of distant objects. He obtained a British patent on September 23, 1904 for his apparatus which he called a Telemobiloscope. Hülsmeyer is often credited with the invention of radar, but his "Telemobiloscope," could not directly measure distance to a target and thus does not merit this full distinction.

The method of using radar to pinpoint small targets was developed independently in Britain, France, Germany, and the US in the 1930s.

In 1935 Robert Watson-Watt carried out a demonstration near Daventry which led directly to the development of RADAR in the United Kingdom. Having proved radar detection technology could work Watson-Watt received a patent for his system, on September 1, 1936.

The first workable unit built by Robert Watson-Watt and his team

The Type 79 radar was the first radar system deployed by the Royal Navy. The first version of this radar, Type 79X, was mounted on the RN Signal School's tender, the minesweeper HMS Saltburn, in October 1936.

The British Army's first radar system, the Gun Laying radar, used up the nation's entire stockpile of chicken wire.

Radar was first put to practical use for aircraft detection by the British, who had a complete coastal chain of radar sets installed in time for the outbreak of World War II in 1939. This system provided the vital advance information that helped the Royal Air Force win the Battle of Britain when the ability to spot incoming German aircraft did away with the need to fly standing patrols.

The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. This acronym of American origin replaced the previously used British abbreviation RDF (Radio Direction Finding). The term has since entered the English language as a standard word, radar, losing the capitalization in the process.

The Northamptonshire-born mathematician Dame Mary Cartwright (1900-1998) was the first woman to serve on the Royal Society council and as president of the London Mathematical Society. Her work was critical in perfecting radar equipment, saving countless lives in World War II. She hated praise and once wrote to scold a scientist for crediting her with more than she deserved.

During World War II, as a RAF officer, the science fiction writer Arthur C Clarke was in charge of the first radar talk-down equipment, the Ground Controlled Approach, during its experimental trials.

On February 15 1954 Canada and the United States agreed to construct the Distant Early Warning Line, a system of radar stations in the far northern Arctic regions of Canada and Alaska.

POW-2, now Oliktok Long Range Radar Site

Saturday, 17 June 2017

Racket

Records confirm that tennis was played in France in the twelfth century, at first with the palm of the hand only. Rackets then were still unknown.

The etymology of the word racket (or racquet), as in tennis, can be traced via the French raquette to the Arab rahat, a colloquial form of raha - the palm of the hand. That is why the logical Frenchman came to call the sport not tennis but "the game of the hand."


These early tennis players soon came to realize that striking the ball with their bare hands could hurt very much. Therefore, to soften the blow, players began to wear gloves. Not only did the glove guard against injury, it gave the ball greater impetus.

All that was further needed was to take off the improved glove and add a handle and strings to it. The first wooden-framed rackets, strung with sheep gut, appeared in the 15th century.

Early advertisement for tennis rackets, from an English newspaper.

Table tennis began, though not under that name, as a parlor game in Victorian homes. The equipment used in those early days was mostly improvised and home-made. The racket or bat was cut out of a piece of thick cardboard. The rubber-covered racket didn't come into play until 1905.

A badminton racket has a longer, thinner neck than a tennis racket with softer strings as the shuttlecock is hit up over a net.

Throughout most of tennis' history, rackets were made of laminated wood. In the late 1960s, Wilson produced the T2000 steel racket with wire wound around the frame to make string loops. It was popularized by the American tennis star Jimmy Connors.

A United States tennis racket from the 1970s

In the early 1980s, "graphite" (carbon fibre) composites were introduced, and other materials were added to the composite, including ceramics, glass-fibre, boron, and titanium. Composite rackets are the contemporary standard, the last wooden racket appeared at Wimbledon in 1987.

Source Europress Encyclopedia