Tetralogy of Fallot

Tetralogy of Fallot (TOF) is a congenital heart defect which is classically understood to involve four anatomical abnormalities of the heart (although only three of them are always present). It is the most common cyanotic heart defect and the most common cause of blue baby syndrome. TOF is usually a right-to-left shunt, in which higher resistance to right ventricular outflow results in more severe cyanosis symptoms.

TOF is treated with corrective surgery, usually within the first year of life, but presents with long-term problems including arrhythmia, pulmonary regurgitation, and re-operation.

In the United States, the prevalence of TOF is 3.9 per 10,000 live births and accounts for 7-10% of congenital heart diseases. It was described in 1672 by Niels Stensen, in 1773 by Edward Sandifort, and in 1888 by the French physician Étienne-Louis Arthur Fallot, after whom it is named.

Signs and symptoms

Tetralogy of Fallot results in low oxygenation of blood due to the mixing of oxygenated and deoxygenated blood in the left ventricle via the ventricular septal defect (VSD) and preferential flow of the mixed blood from both ventricles through the aorta because of the obstruction to flow through the pulmonary valve. This is known as a right-to-left shunt. The primary symptom is low blood oxygen saturation with or without cyanosis from birth or developing in the first year of life. If the baby is not cyanotic then it is sometimes referred to as a "pink tet." Other symptoms include a heart murmur which may range from almost imperceptible to very loud, difficulty in feeding, failure to gain weight, retarded growth and physical development, dyspnea on exertion, clubbing of the fingers and toes, and polycythemia.

Tetralogy

A tetralogy (from Greek τετρα- tetra-, "four" and -λογία -logia, "discourse") is a compound work that is made up of four distinct works. The name comes from the Attic theater, in which a tetralogy was a group of three tragedies followed by a satyr play, all by one author, to be played in one sitting at the Dionysia as part of a competition.

Antiphon of Rhamnus, an orator, taught his students with Tetralogies, each one consisting of four speeches: the prosecutor's opening speech, the first speech for the defence, the prosecutor's reply, and the defendant's conclusion. Three of Antiphon's tetralogies survive. In more recent times, Shakespeare wrote two tetralogies, the first consisting of the three Henry VI plays and Richard III, and the second consisting of Richard II, the two Henry IV plays, and Henry V. Richard Wagner's Der Ring des Nibelungen ("The Ring of the Nibelung" or "The Ring Cycle") is also referred to as a tetralogy.

As an alternative to "tetralogy", "quartet" is sometimes used, particularly for series of four books. The term "quadrilogy", basing the prefix on Latin prefix quadri- instead of the Greek prefix, and first recorded in 1865, has also been used for marketing series of movies, such as the Alien series.

Khan Academy

Khan Academy is a non-profit educational organization created in 2006 by educator Salman Khan with the aim of providing a free, world-class education for anyone, anywhere. The organization produces short lectures in the form of YouTube videos. In addition to micro lectures, the organization's website features practice exercises and tools for educators. All resources are available for free to anyone around the world. The main language of the website is English, but the content is also available in other languages.

History

The founder of the organization, Salman Khan, was born in New Orleans, Louisiana, United States to immigrant parents from Bangladesh and India. After earning three degrees from the Massachusetts Institute of Technology (a BS in mathematics, a BS in electrical engineering and computer science, and an MEng in electrical engineering and computer science), he pursued an MBA from Harvard Business School.

In late 2004, Khan began tutoring his cousin Nadia who needed help with math using Yahoo!'s Doodle notepad.When other relatives and friends sought similar help, he decided that it would be more practical to distribute the tutorials on YouTube. The videos' popularity and the testimonials of appreciative students prompted Khan to quit his job in finance as a hedge fund analyst at Connective Capital Management in 2009, and focus on the tutorials (then released under the moniker "Khan Academy") full-time.

Ace Frehley

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Paul Daniel "Ace" Frehley (/ˈfreɪli/; born April 27, 1951) is an American musician, singer and songwriter best known as the former lead guitarist and founding member of the rock band Kiss. He took on the persona of the "Spaceman" or "Space Ace" and played with the group from its inception in 1973 until his departure in 1982. After leaving Kiss, Frehley embarked on a solo career, which was put on hold when he rejoined Kiss in 1996 for a highly successful reunion tour.

His second tenure with Kiss lasted until 2002, when he left at the conclusion of what was originally purported to be the band's Farewell Tour. His most recent solo album, Space Invader, was released on August 19, 2014. Guitar World magazine ranked him as the 14th Greatest Metal Guitarist of All Time. His solos often incorporate the minor pentatonic scale and the usage of vibratos. Outside of Kiss, Frehley has continued to be commercially successful, with his first solo album going platinum. Frehley is also known for the use of many "whimsical" guitars, including a Gibson Les Paul guitar that emits smoke from the neck humbucker pickup and produces spinning pyrotechnics, and a custom Les Paul that emits light based on song tempo.