The calcium carbonate or silica spicules of most sponges make them too rough for most uses, but two genera, "Hippospongia" and "Spongia", have soft, entirely fibrous skeletons. Early Europeans used soft sponges for many purposes including padding for helmets, portable drinking utensils and municipal water filters. Until synthetic sponges were invented, they were also used as cleaning tools, for painting, and as contraceptives. In the 20th century, overfishing is a problem. This has caused the animals, as well as the industry behind it to be close to extinction.
Many objects with sponge-like textures are now made of substances that do not come from poriferans. Synthetic "sponges" include personal and household cleaning tools; breast implants; contraceptive sponges.
The luffa "sponge", also spelled "loofah", which is commonly sold for use in the kitchen or the bath, is not derived from an animal but from the fibrous "skeleton" of a gourd (Cucurbitaceae).
Kibibyte
A kibibyte is a unit of information or computer storage. A kibibyte is 1024 bytes, 1024 kibibytes are a mebibyte.
Lara Croft Tomb Raider: The Cradle of Life
Tomb Raider: The Cradle of Life is a 2003 action movie from Paramount Pictures. It is the second movie to star Angelina Jolie as the title character from the "Tomb Raider" video games.
Amplitude
The amplitude or peak amplitude of a wave is a measure of how big its oscillation is.
Amplitudes are always measured as positive numbers (for example: 3.5, 1, 120) and are never negative (for example: -3.5, -1, -120). That's because distance can only be greater than zero or equal to zero; negative distance does not exist.
The distance from the top of one peak to the bottom of another is called "peak-to-peak amplitude". Another way to describe peak-to-peak amplitude is to say that it is the distance between the maximum positive value and the maximum negative value of a wave is the maximum displacement of a wave from an equilibrium position
Ska
Ska is a popular music from Jamaica that began in the 1950s. Ska music that was first played at a slower tempo then became reggae in the late 1960s.
Ska music bands include singers, electric guitars, electric bass guitar, piano, organ, saxophone, trumpet, and trombone. In ska, the electric guitar and piano normally play short chords on the off-beat. If you go "one and two and three and four", the off-beat is the "and".
A ska singer does a style of Jamaican singing called "toasting." When a singer is "toasting", they make sounds, repeat words, invent rhymes, and shout into the microphone. The Jamaican "toasting" style of singing and talking was adapted into rap music in the 1980s.
Musicians who play ska dress in hats and suits. Many ska bands wear clothes with a chessboard pattern of black and white squares. Doc Martens are a common type of shoe. This pattern symbolizes the way that ska music mixes of Black and White musicans and styles of music.There was a British genre of ska-punk influenced by The Specials, Madness and the English Beat, that began to dress in kilts.
Even though ska was developed in the 1950s, it became popular again in the 1980s in Britain. In the 1980s, ska bands such as The Specials, The Selecter, The Beat, UB40 and Madness played ska music.
In the 1990s, some bands mixed ska music with Punk rock to make ska-punk. This kind of ska music is from England and the United States. Some pop-punk bands from the 1990s mixed pop-punk with ska-punk.
Braille
The Braille system is a way of writing things. It is named after Louis Braille, the French man who invented it. The system is used by blind people to read and write. The Braille system uses a set of raised bumps or dots that can be felt with a finger. Each set of dots is a character in an alphabet, and the numbers and some punctuation.
Louis Braille was not the first person to think about how to let the blind read and write. In the 17th century the Italian Jesuit Francesco Lana thought about different systems of writing for the blind. He invented a system of dashes that could be felt.
Valentin Haüy was one of the first French who was interested in the problems the blind had when they wanted to communicate. Haüy was born in Picardie in 1745, and studied languages at the university in Paris. First he studied deaf people who could not speak, then blind people. In his opinion the biggest problem of the blind was that they could not read. He then invented a system which allowed them to read and write sentences and to do mathematics. Later he started a school for blind children. His writing system used two columns which had between one and six positions each. Vowels had a dot in the left column, for example.
Charles Barbier used a similar system, because Napoleon wanted a code that soldiers could use to exchange messages silently and without light at night. Barbier called it night writing. Night writing uses two columns of six dots. It uses phonemes (separate sounds), not letters. Barbier's system was too hard for soldiers to learn, and the military did not use it. From the year 1821, he started to test his system in the school Haüy had founded. There it became very successful. Even though the system was difficult to learn, it did help the blind to read better than earlier systems. Barbier had understood that it was better to use a system that used dots over one that used lines.
Barbier met Braille when he visited the National Institute of the Blind. Braille saw the biggest problem of the code: The human finger cannot feel the whole symbol at one time. This makes it impossible to move rapidly from one symbol to the next. Braille's change was to use a 6 dot cell — the braille system — which completely changed how the blind would read and write.
Braille can be seen as the world's first binary way of character encoding. The system as originally invented by Braille has two parts
Braille is used with different languages today. In each language, the letters are "encoded" differently, depending on the alphabet. The list of codes is known as braille code, or code page. There are also different braille codes in use for special purposes, like writing shorthand, mathematics or music.
To make it possible to read faster, certain transcriptions of Braille use shortened words, or contractions. This is known as "Grade 2 Braille".
Braille uses cells of six raised dots, in two columns of three dots. The dot positions on the left are numbered one, to three, the ones on the right four to six, as shown in the picture.
Each symbol is coded with certain dots present, and others absent. The dots are approximately 0.02 inches (0.5 mm) high; inside the cell, the dots are about 0.1 inches (2.5 mm) apart. The space between the dots of two cells is about 0.15 inches (3.75 mm) horizontally and 0.2 inches (5 mm) vertically. A standard braille page is 11 inches by 11 inches and typically has between forty and forty-two braille cells per line and twenty-five lines.
As first made by Louis Braille, the first group of characters, using just the top 4 dots of the braille cell, represents letters "a" through "j" (this group of ten characters is called a "decade"). Dot 3 (bottom left) is added to each of the "a" through "j" symbols to give letters "k" through "t". Both of the bottom dots (dots 3 and 6) are added to the first decade to give letters "u", "v", "x", "y", and "z". The letter "w" is left out of this group because French did not use the letter "w" when Louis Braille made his alphabet. The fifth decade is the same as the first decade, but shifted down by a row (dots 1 and 4 are blank).
English braille has codes for the letters and some punctuation, and some double letter signs and word signs directly, but capitalization and numbers need a prefix symbol. In practice, braille produced in the United Kingdom does not use capital letters.