title: Hyuna

text: In 2011, Hyuna appeared in the Korean version of "Dancing with the Stars". The show began broadcasting on June 10. The same year, she released her first mini album, "Bubble Pop", featuring five new songs including the title track of the same name. The single was a global success, and featured on top of YouTube's "most watched today" chart after gaining one million views in two days. It eventually became the first music video by a K-pop artist to surpass 100 million views. Hyuna was ranked 17th on Billboard<nowiki>'</nowiki>s '21 Under 21′, a staff-compiled list of notable young acts; while "Bubble Pop" was listed as ninth place on Spin magazine's "Best 20 Songs of 2011." On November 24, 2011, Cube revealed that she would be in a co-ed unit called Trouble Maker with BEAST's Hyunseung. Trouble Maker's first mini album, "Trouble Maker", consisted of a dance track and an emotional ballad, as well as solo songs for both Hyuna and Hyunseung. Trouble Maker performed for the first time at the Mnet Asian Music Awards.


title: Hyuna

text: In March 2012, she joined "The Birth of a Family", an "animal communion variety" program where idols adopt stray pets and take care of them for a certain period of time to raise awareness for animal rights. On March 14, Hyuna announced the launch of her brand "Hyuna x SPICYCOLOR". She also appeared in Psy's viral music video for "Gangnam Style," having been selected personally by Psy during the initial production stage. "Gangnam Style" became the most viewed K-pop music video, and drew worldwide global recognition for Hyuna. Psy released the female version of "Gangnam Style", known as "Oppa Is Just My Style" in August 2012, featuring additional vocals by Hyuna herself. Hyuna released her second mini album titled "Melting" on October 21, 2012 with the title track "Ice Cream". The song was produced by Brave Brothers and was the first collaborative effort between the producer and Hyuna as a solo artist. The video for Ice Cream was released on October 22, 2012 and features a cameo by Psy. "Ice Cream" drew global attention, after being featured by several international media outlets. It drew a record number of views on YouTube and became the then-fastest Korean music video to reach 20 million views. "Melting" is also notable for Hyuna's contributions as a lyricist and composer for "Very Hot" and "To My Boyfriend". In the same month, it was announced that she would join four other K-pop stars; Sistar's Hyolyn, Secret's Jun Hyo-seong, After School's Nana and Kara's Nicole to form a project group titled "Dazzling Red". The group performed at the 2012 SBS Gayo Daejeon.


title: Hyuna

text: On May 24, Hyuna collaborated with makeup artists Son & Park to launch a series of charitable activities titled "Kiss of Hope", whose profits were donated to the education of children in poor countries. In March, she became a spokesmodel for the 2013 Toyota Corolla. Hyuna released the short music video "Corolla x Hyuna: My Color", and the "Corolla x Hyuna" mobile app which teaches her song and choreography. On March 11, she performed at the K-Pop Night Out at SXSW at Austin, Texas. Hyuna then went to Los Angeles to film a "Funny or Die" sketch with British singer Rita Ora. The two stars' "Better Walk" video was released on "Funny or Die" on April 2, 2014. In October, she and Hyunseung made a comeback as Trouble Maker. They released the single "Now" from their "Chemistry" EP. The song reached number one on ten of Korea's major music charts, and was deemed by Instiz.net as an All-Kill. It also topped "Billboard" K-Pop Hot 100 chart. In July 2014, she released her third album titled "A Talk" and its lead single "Red". To promote the album, Hyuna appeared in her own reality show titled "Hyuna's Free Month", which showcased various aspects of her daily life. "Red" proved to be a success, with Billboard praising her for establishing herself as a global pop brand and Rolling Stone naming "Red" number five on their list of the top ten music videos of 2014. The album also topped charts in Taiwan. In August 2015, she released her fourth mini album "A+", with the lead single titled "Because I'm the Best" featuring Jung Il-hoon. Hyuna made her comeback on "M! Countdown" and performed "Ice, Ice" featuring Hwasa.


title: Hyuna

text: On June 13, 2016, it was announced that 4Minute had made the decision to disband. Hyuna was the only member of the group to renew her contract with Cube Entertainment. Following the group's disbandment, she resumed her activities as a solo artist, with the release of her fifth mini album "A'wesome" and its title track "How's This?" (), on August 1, 2016. Behind-the-scenes footage of Hyuna's album's preparation was featured on her solo reality program "HyunA X19". The album topped nine local music charts upon release. She embarked on her first solo Asia tour soon after. To mark her tenth anniversary, Hyuna announced a fan-meeting tour in North America. She visited ten cities in total during February 2017. On April 3, 2017, Cube Entertainment confirmed that she and Pentagon members Hui and E'Dawn were set to debut in May as new sub-unit, Triple H. On April 4, Cube TV debuted a new reality TV program called "Triple H Detective Agency". Hyuna released her sixth mini album "Following" and its title track "Babe" on August 29, 2017. On December 2, 2017, the rapper attended the 2017 Melon Music Awards, where she premiered the single "Lip & Hip". It was officially released two days later.


title: Hyuna

text: On August 2, 2018, photos of Hyuna with Pentagon's E'Dawn were released. Cube Entertainment denied rumors that they were dating, however, she and E’Dawn held an interview with Yeonhap News later that day, admitting to their relationship which began in May 2016, after they had got to know each other through their project group Triple H promotions. The company responded to Hyuna's confirmation of the dating rumors by cancelling all previously planned performances for Triple H, on-air appearances and fan events including a fan meet-up that was scheduled on the next day. Fans were divided in reactions to the event, with some calling for E'Dawn to be removed from Pentagon, and others focusing on how the company mistreated her and E'Dawn after releasing the scandal, rather than on their relationship. On September 13, Cube Entertainment announced that they would be terminating their contracts, citing that they could not "maintain trust" with them. However, the company announced that they would still remain in discussion with both of them until further notice. Cube Entertainment cited "loss of trust" as a reason saying "After much deliberation, we've concluded that the trust between the company and the artists had been damaged to a degree that it cannot be restored, leading us to believe expulsion is necessary," in its official statement. On October 15, Cube Entertainment officially confirmed Hyuna's departure.


title: Hyuna

text: On January 27, 2019, she signed with P Nation, a new agency founded by Psy since he left YG Entertainment in May 2018. On November 5, 2019, she released a single titled "Flower Shower", her first release under P Nation. In January 2021, P Nation announced Hyuna's first comeback since "Flower Shower", with the release of her seventh EP "I'm Not Cool" and its title track of the same name, which was released on January 28. On September 9, 2021, Hyuna and Dawn collaborated to release their duet EP "1+1=1".


title: Hyuna

text: On June 7, 2022, it was announced that Hyuna would be attending the "J-Rim Super Nova Festival" with E'Dawn, taking place on July 2-3, 2022.


title: Hyuna

text: On August 29, 2022, P Nation announced that Hyuna would be leaving the company after deciding not to renew her contract.


title: Hyuna

text: On August 2, 2018, Hyuna revealed that she has been in a relationship with Pentagon member E'Dawn since May 2016. They got engaged on February 3, 2022, with the couple posting the announcement on Instagram. In November 2022, Hyuna posted on her Instagram account that the couple had separated.


title: Hyuna

text: On November 28, 2019, Hyuna posted a letter on Instagram where she opened up about her health. She revealed that, in 2016, she was diagnosed with depression and panic disorder. Additionally, she revealed she experienced foggy vision, causing her to collapse. Thinking they were symptoms of her panic disorder, she ignored it. However, after seeing a doctor, she received a brain wave test that concluded a diagnosis of vasovagal syncope. The following year Hyuna opened up about her struggles on MBC's Radio star, where she stated that she is struggling nearly 10 years from vasovagal syncope.


title: Hyuna

text: On March 15, 2018 Hyuna became the ambassador for the German brand Puma, where she digested the two opposing concepts of 'Pink or Black" for the brand's campaign. On March 19, 2019, Hyuna released pictorial and a video, for 'Puma Light Sandals' campaign, where she appeared as the brand ambassador alongside Dawn. Later in 2019 Hyuna inked endorsement deal with the brand again, where she released a pictorial and a video for 'Trail Fox' campaign. In March 2020, Calvin Klein announced Hyuna as their ambassador for the "CK ONE" collections. In July 13, 2021, Spanish fashion house Loewe announced that they selected Hyuna as their new global ambassador.


title: Felicia Day

text: Kathryn Felicia Day (born June 28, 1979) is an American actress, writer, and web series creator. She is the creator and star of the web series "The Guild" (2007–2013), a show loosely based on her life as a gamer. She also wrote and starred in the "Dragon Age" web series "" (2011). She is a founder of the online media company Geek & Sundry, best known for hosting the show "Critical Role" between 2015 and 2019. Day was a member of the board of directors of the International Academy of Web Television beginning December 2009 until the end of July 2012.


title: Felicia Day

text: On television, Day has played Vi in the series "Buffy the Vampire Slayer" (2003) and Dr. Holly Marten in "Eureka" (2011), and had a recurring role as Charlie Bradbury on "Supernatural" (2012–2015, 2018–2020). She has also acted in movies such as "Bring It On Again" (2004), as well as the Internet musical "Dr. Horrible's Sing-Along Blog" (2008). In April 2017, she began appearing as Kinga Forrester in "Mystery Science Theater 3000".


title: Felicia Day

text: Day was born in Huntsville, Alabama. She began her acting career at the age of 7 when she starred as Scout in a local production of "To Kill a Mockingbird". She studied operatic singing and ballet professionally, performing at concerts and competitions nationwide. Home-schooled throughout much of her childhood, she began college at the age of 16.


title: Felicia Day

text: She was a National Merit Scholar (1995) and graduated as valedictorian of her class. An accomplished violinist, Day was accepted to the Juilliard School of Music but chose to attend the University of Texas at Austin on a full scholarship in violin performance. She double majored in mathematics and music performance, and graduated at the age of 19 in the top 4% of her class. She is also an avid player of a wide variety of video game genres. Much of her work on "The Guild" web series was based on her personal experience with video games, especially when she played "World of Warcraft".


title: Felicia Day

text: After graduation, Day moved to Los Angeles to pursue a career in acting. She landed several roles in various short and independent films as well as commercials and guest spots on television shows, including "Undeclared" and "Maybe It's Me". These parts propelled her to larger roles: a part in the film "Bring It On Again", the starring role in "June", and a recurring guest spot as potential Slayer Vi on television's "Buffy the Vampire Slayer", a recurring role that is still occasionally used in that show's eighth season comic book series. In HBO's 2005 biopic of Franklin D. Roosevelt, "Warm Springs", Day's singing was featured when her wheelchair-using character serenaded a dinner group with "I Won't Dance".


title: Felicia Day

text: Day is the creator, writer, and star of "The Guild", a web series which aired from 2007 to 2013 and explored the MMORPG gaming subculture. The first season was primarily hosted on YouTube, where it garnered millions of views. Its second season premiered on Microsoft's three major video channels, Xbox Live, MSN Video and The Zune Marketplace, after Microsoft made a deal with "The Guild", allowing Day, her cast and her crew to be paid for their work.


title: Felicia Day

text: Day also created a song and music video called "(Do You Wanna Date My) Avatar", featuring the cast dressed up as their in-game personae. The final moments of the music video itself also detailed that the release date for the third season of Day's "The Guild" would be August 25, 2009. A second song and Bollywood style video "Game On" was released prior to the premiere of the fourth season of "The Guild". A third and final music video, called "I'm the One That's Cool", features the members of the cast in the guise of an alternative band performing at a local venue, intercut with scenes of the cast as younger versions of their characters experiencing bullying at the hands of "cooler" and more popular kids while at school.


title: Felicia Day

text: "The Guild" has won multiple awards, including the Greenlight Award for Best Original Digital Series Production at the South by Southwest festivals, several IAWTV Awards, including Best Comedy Series, the YouTube Video Award for Best Series, the Yahoo! Video Award for Best Series, and 2009 Streamy Awards for Best Comedy Web Series, Best Female Actor in a Comedy Web Series, and Best Ensemble Cast in a Web Series.


title: Felicia Day

text: In March 2012, Day announced that she would be launching a premium YouTube channel, "Geek & Sundry," on April 2.


title: Felicia Day

text: Geek and Sundry took over production of "The Guild" for Season 6. Day hosts several shows on Geek & Sundry, most notably "The Flog," "Vaginal Fantasy," "Felicia's Ark," and "Co-Optitude" (which co-stars Felicia's brother Ryon Day.)


title: Felicia Day

text: In 2012 Day created the web series "Tabletop" with Wil Wheaton. She is an executive producer for the series and appears regularly as a guest. In the same vein, in 2015 she suggested to the original cast of Critical Role to begin streaming their tabletop home game as a show.


title: Felicia Day

text: In August 2014, Geek and Sundry was acquired by Legendary to produce content alongside of Chris Hardwick's Nerdist Industries, with Day retaining creative control.


title: Felicia Day

text: In July 2008, Day starred as Penny in the three-part web-based musical "Dr. Horrible's Sing-Along Blog" (created by Joss Whedon, who also created "Dollhouse" and "Buffy the Vampire Slayer", in which Day had parts). Day was featured as a patient in the episode "Not Cancer" of the medical drama "House", and had a guest starring role in an unaired episode of sci-fi drama "Dollhouse" entitled "Epitaph One", as well as its series finale "." Also in 2008, Day was featured in a series of commercials for Sears Blue Crew. She also appeared in the first of the revitalized Cheetos commercials.


title: Felicia Day

text: In the series "Lie to Me", on the episode called "Tractor Man," airing December 14, 2009, Day sang a song called "White Lie" alongside Brendan Hines. Day starred with Kavan Smith in the Syfy film adaption of the Little Red Riding Hood saga, called "Red," produced by Angela Mancuso. Day also played the continuing role of Dr. Holly Marten in the Syfy channel's original series, "Eureka", appearing in 18 episodes during the last two seasons of the show. Day has also played the role of 'Gorgol' in the web series "MyMusic" directed by The Fine Brothers.


title: Felicia Day

text: In February 2011, Day announced that she would be starring in a new web miniseries called "", based on the "Dragon Age" video game series developed by BioWare and aired on October 10, 2011. Day plays an elf named Tallis, and returns as the voice and likeness for the character in the "Dragon Age II" downloadable content "Mark of the Assassin".


title: Felicia Day

text: In January 2012, Day announced that she would be hosting a Google+ Hangout called Vaginal Fantasy. The Hangout featured Day along with Kiala Kazebee, Veronica Belmont, and Bonnie Burton. Every month they discussed lady-leaning paranormal and historical adventure books. In February 2012, Day guest starred in Sean "Day[9]" Plott's online webcast featuring "".


title: Felicia Day

text: In April 2012, it was announced that Day would host the 2012 IndieCade Awards Ceremony on October 4, 2012. Also in April of that year, Day appeared on the YouTube show MyMusic as a Norwegian Black Metal singer named Gorgol. She guest starred in the second season of the Jane Espenson scripted web series, "Husbands". In October 2012, she guest starred on The Game Station podcast and appeared in an episode of "My Drunk Kitchen".


title: Felicia Day

text: In 2013, Geek & Sundry and Atlas Games worked together to release a promotional pack for the card game "Gloom" for TableTop Day 2013 with a "Felicia Day, Guild Goddess" card. In 2014, Alderac Entertainment Group included a "Felicia Day" card in the storage case expansion, "The Big Geeky Box" for their card game "Smash Up". In 2015, Plaid Hat Games released a Felicia Day character card for their board game "" for Tabletop Day 2015.


title: Felicia Day

text: On August 4, 2015, Day guest starred on Episode 9 of the "Dear Hank & John" podcast. On October 1, 2016, Day provided a guest voice for the "Welcome to Night Vale" podcast as Zookeeper Joanna Rey.


title: Felicia Day

text: In April 2017, she began appearing as Kinga Forrester in "Mystery Science Theater 3000". In August 2017, Day appeared as a guest in the "" episode "The Perfect Pear", voicing Pear "Buttercup" Butter, the presumed-deceased mother of one of the show's main characters, Applejack. In the episode, she also performs a romantic ballad, titled "You're In My Head Like a Catchy Song".


title: Felicia Day

text: Day organised and hosted a Twitch charity livestream on June 30, 2018, in aid of Refugee and Immigrant Center for Education and Legal Services (RAICES), a Texas nonprofit. The 12-hour livestream raised over $212,000.


title: Felicia Day

text: From 2018 to 2019, Day appeared in four episodes of the Syfy channel original series "The Magicians" as Poppy Kline.


title: Felicia Day

text: During the inaugural Streamy Awards held in Los Angeles on March 28, 2009, Day received the award for the "Best Female Actor in a Comedy" for her work as protagonist Cyd Sherman in "The Guild," and won the same award again in 2010.


title: Felicia Day

text: She was also recognized for her work on "Dr. Horrible's Sing-Along Blog" in 2009. Day was also nominated for the Best Guest Appearance Award for the 3rd Streamy Awards.


title: Felicia Day

text: In June 2018, she won a Behind the Voice Actors Award in Best Female Vocal Performance in a Television Series in a Guest Role for her role as Pear Butter in the episode "The Perfect Pear".


title: Felicia Day

text: On January 3, 2017, Day announced on social media that she was pregnant and expecting a baby girl in a few weeks. She announced her daughter's birth on January 30, 2017.


title: Felicia Day

text: Day is the author of the memoir "You're Never Weird on the Internet (Almost)", "Embrace Your Weird: Face Your Fears and Unleash Creativity", as well as numerous works relating to "The Guild" web series.


title: Cogito, ergo sum

text: The Latin , usually translated into English as "I think, therefore I am", is the "first principle" of René Descartes's philosophy. He originally published it in French as , in his 1637 "Discourse on the Method", so as to reach a wider audience than Latin would have allowed. It later appeared in Latin in his "Principles of Philosophy", and a similar phrase also featured prominently in his "Meditations on First Philosophy". The dictum is also sometimes referred to as the cogito. As Descartes explained in a margin note, "we cannot doubt of our existence while we doubt." In the posthumously published "The Search for Truth by Natural Light", he expressed this insight as ("I doubt, therefore I am — or what is the same — I think, therefore I am"). Antoine Léonard Thomas, in a 1765 essay in honor of Descartes presented it as ("I doubt, therefore I think, therefore I am").


title: Cogito, ergo sum

text: Descartes's statement became a fundamental element of Western philosophy, as it purported to provide a certain foundation for knowledge in the face of radical doubt. While other knowledge could be a figment of imagination, deception, or mistake, Descartes asserted that the very act of doubting one's own existence served—at minimum—as proof of the reality of one's own mind; there must be a thinking entity—in this case the self—for there to be a thought.


title: Cogito, ergo sum

text: One critique of the dictum, first suggested by Pierre Gassendi, is that it presupposes that there is an "I" which must be doing the thinking. According to this line of criticism, the most that Descartes was entitled to say was that "thinking is occurring", not that "I am thinking".


title: Cogito, ergo sum

text: Descartes first wrote the phrase in French in his 1637 "Discourse on the Method". He referred to it in Latin without explicitly stating the familiar form of the phrase in his 1641 "Meditations on First Philosophy". The earliest written record of the phrase in Latin is in his 1644 "Principles of Philosophy", where, in a margin note (see below), he provides a clear explanation of his intent: "[W]e cannot doubt of our existence while we doubt". Fuller forms of the phrase are attributable to other authors.


title: Cogito, ergo sum

text: The phrase first appeared (in French) in Descartes's 1637 "Discourse on the Method" in the first paragraph of its fourth part:


title: Cogito, ergo sum

text: In 1641, Descartes published (in Latin) "Meditations on first philosophy" in which he referred to the proposition, though not explicitly as "cogito, ergo sum" in Meditation II:


title: Cogito, ergo sum

text: In 1644, Descartes published (in Latin) his "Principles of Philosophy" where the phrase "ego cogito, ergo sum" appears in Part 1, article 7:


title: Cogito, ergo sum

text: Descartes, in a lesser-known posthumously published work dated as written ca. 1647 and titled ("The Search for Truth by Natural Light"), provides his only known phrasing of the cogito as and admits that his insight is also expressible as dubito, ergo sum:


title: Cogito, ergo sum

text: The proposition is sometimes given as . This form was penned by the French literary critic, Antoine Léonard Thomas, in an award-winning 1765 essay in praise of Descartes, where it appeared as "" ('Since I doubt, I think; since I think, I exist'). With rearrangement and compaction, the passage translates to "I doubt, therefore I think, therefore I am," or in Latin, ""dubito, ergo cogito, ergo sum"." This aptly captures Descartes's intent as expressed in his posthumously published "La Recherche de la Vérité par La Lumiere Naturale" as noted above: I doubt, therefore I am — or what is the same — I think, therefore I am.


title: Cogito, ergo sum

text: A further expansion, ("…—a thinking thing") extends the "cogito" with Descartes's statement in the subsequent "Meditation", ("I am a thinking [conscious] thing, that is, a being who doubts, affirms, denies, knows a few objects, and is ignorant of many,-- who loves, hates, wills, refuses, who imagines likewise, and perceives"). This has been referred to as "the expanded "cogito"."


title: Cogito, ergo sum

text: While the Latin translation "cōgitō" may be translated rather easily as "I think/ponder/visualize", does not indicate whether the verb form corresponds to the English simple present or progressive aspect. Technically speaking, the French lemma "pense" by itself is actually the result of numerous different conjugations of the verb "penser" (to think) – it could mean "I think... (something)"/"He thinks... (something)", "I think."/"He thinks.", or even "You (must) think... (something).", thereby necessitating the use of the wider context, or a pronoun, to understand the meaning. In the case of "je pense", a pronoun is already included, "je" or "I", but this still leaves the question of whether "I think..." or "I think." is intended. Therefore, translation needs a larger context to determine aspect.


title: Cogito, ergo sum

text: Following John Lyons (1982), Vladimir Žegarac notes, "The temptation to use the simple present is said to arise from the lack of progressive forms in Latin and French, and from a misinterpretation of the meaning of "cogito" as habitual or generic" (cf. gnomic aspect). Also following Lyons, Ann Banfield writes, "In order for the statement on which Descartes's argument depends to represent certain knowledge,… its tense must be a true present—in English, a progressive,… not as 'I think' but as 'I am thinking, in conformity with the general translation of the Latin or French present tense in such nongeneric, nonstative contexts." Or in the words of Simon Blackburn, "Descartes's premise is not 'I think' in the sense of 'I ski', which can be true even if you are not at the moment skiing. It is supposed to be parallel to 'I am skiing'."


title: Cogito, ergo sum

text: The similar translation "I am thinking, therefore I exist" of Descartes's correspondence in French (", ") appears in "The Philosophical Writings of Descartes" by Cottingham et al. (1988).


title: Cogito, ergo sum

text: The earliest known translation as "I am thinking, therefore I am" is from 1872 by Charles Porterfield Krauth.


title: Cogito, ergo sum

text: Fumitaka Suzuki writes "Taking consideration of Cartesian theory of continuous creation, which theory was developed especially in the Meditations and in the Principles, we would assure that 'I am thinking, therefore I am/exist' is the most appropriate English translation of 'ego cogito, ergo sum'."


title: Cogito, ergo sum

text: Alexis Deodato S. Itao notes that is "literally 'I think, therefore I am'." Others differ: 1) "[A] precise English translation will read as 'I am thinking, therefore I exist'.; and 2) "[S]ince Descartes ... emphasized that existence is such an important 'notion,' a better translation is 'I am thinking, therefore I exist.'"


title: Cogito, ergo sum

text: Descartes wrote this phrase as such only once, in the posthumously published lesser-known work noted above,"The Search for Truth by Natural Light". It appeared there mid-sentence, uncapitalized, and with a comma. (Commas were not used in Classical Latin but were a regular feature of scholastic Latin, the Latin Descartes "had learned in a Jesuit college at La Flèche.") Most modern reference works show it with a comma, but it is often presented without a comma in academic work and in popular usage. In Descartes's "Principia Philosophiae", the proposition appears as ego cogito, ergo sum.


title: Cogito, ergo sum

text: As put succinctly by Krauth (1872), "That cannot doubt which does not think, and that cannot think which does not exist. I doubt, I think, I exist."


title: Cogito, ergo sum

text: The phrase "cogito, ergo sum" is not used in Descartes's "Meditations on First Philosophy" but the term "the "cogito"" is used to refer to an argument from it. In the "Meditations", Descartes phrases the conclusion of the argument as "that the proposition, "I am, I exist," is necessarily true whenever it is put forward by me or conceived in my mind" ("Meditation" II). George Henry Lewes says Descartes "has told us that [his objective] was to find a starting point from which to reason—to find an irreversible certainty. And where did he find this? In his own consciousness. Doubt as I may, I cannot doubt of my own existence, because my very doubts reveal to me a something which doubts. You may call this an assumption, if you will; I point out the fact as one above and beyond all logic; which logic can neither prove nor disprove; but which must always remain an irreversible certainty, and as such a fitting basis of philosophy."


title: Cogito, ergo sum

text: At the beginning of the second meditation, having reached what he considers to be the ultimate level of doubt—his argument from the existence of a deceiving god—Descartes examines his beliefs to see if any have survived the doubt. In his belief in his own existence, he finds that it is impossible to doubt that he exists. Even if there were a deceiving god (or an evil demon), one's belief in their own existence would be secure, for there is no way one could be deceived unless one existed in order to be deceived.


title: Cogito, ergo sum

text: There are three important notes to keep in mind here. First, he claims only the certainty of "his own" existence from the first-person point of view — he has not proved the existence of other minds at this point. This is something that has to be thought through by each of us for ourselves, as we follow the course of the meditations. Second, he does not say that his existence is necessary; he says that "if he thinks", then necessarily he exists (see the instantiation principle). Third, this proposition "I am, I exist" is held true not based on a deduction (as mentioned above) or on empirical induction but on the clarity and self-evidence of the proposition. Descartes does not use this first certainty, the "cogito", as a foundation upon which to build further knowledge; rather, it is the firm ground upon which he can stand as he works to discover further truths. As he puts it:


title: Cogito, ergo sum

text: According to many Descartes specialists, including Étienne Gilson, the goal of Descartes in establishing this first truth is to demonstrate the capacity of his criterion — the immediate clarity and distinctiveness of self-evident propositions — to establish true and justified propositions despite having adopted a method of generalized doubt. As a consequence of this demonstration, Descartes considers science and mathematics to be justified to the extent that their proposals are established on a similarly immediate clarity, distinctiveness, and self-evidence that presents itself to the mind. The originality of Descartes's thinking, therefore, is not so much in expressing the "cogito"—a feat accomplished by other predecessors, as we shall see—but on using the "cogito" as demonstrating the most fundamental epistemological principle, that science and mathematics are justified by relying on clarity, distinctiveness, and self-evidence.


title: Cogito, ergo sum

text: Baruch Spinoza in ""Principia philosophiae cartesianae"" at its "Prolegomenon" identified "cogito ergo sum" the ""ego sum cogitans"" (I am a thinking being) as the thinking substance with his ontological interpretation.


title: Cogito, ergo sum

text: Although the idea expressed in "cogito, ergo sum" is widely attributed to Descartes, he was not the first to mention it. Plato spoke about the "knowledge of knowledge" (Greek: νόησις νοήσεως, "nóesis noéseos") and Aristotle explains the idea in full length:


title: Cogito, ergo sum

text: The Cartesian statement was interpreted to be an Aristotelian syllogism where is not explicited the premise according to which all thinkers shall be also beings.


title: Cogito, ergo sum

text: In the late sixth or early fifth century BC, Parmenides is quoted as saying "For to be aware and to be are the same". (Fragment B3)


title: Cogito, ergo sum

text: In the early fifth century AD, Augustine of Hippo in "De Civitate Dei" (book XI, 26) affirmed his certain knowledge of his own existence, and added: "So far as these truths are concerned, I do not at all fear the arguments of the Academics when they say, What if you are mistaken? For if I am mistaken, I exist." This formulation () is sometimes called the Augustinian . In 1640, Descartes wrote to thank Andreas Colvius (a friend of Descartes's mentor, Isaac Beeckman) for drawing his attention to Augustine:


title: Cogito, ergo sum

text: Another predecessor was Avicenna's "Floating Man" thought experiment on human self-awareness and self-consciousness.


title: Cogito, ergo sum

text: The 8th century Hindu philosopher Adi Shankara wrote, in a similar fashion, that no one thinks 'I am not', arguing that one's existence cannot be doubted, as there must be someone there to doubt. The central idea of "cogito, ergo sum" is also the topic of "Mandukya Upanishad".


title: Cogito, ergo sum

text: Spanish philosopher Gómez Pereira in his 1554 work "De Inmortalitate Animae", published in 1749, wrote ""nosco me aliquid noscere, & quidquid noscit, est, ergo ego sum"" ('I know that I know something, anyone who knows exists, then I exist').


title: Cogito, ergo sum

text: In "Descartes, The Project of Pure Enquiry", Bernard Williams provides a history and full evaluation of this issue. The first to raise the "I" problem was Pierre Gassendi, who in his , as noted by Saul Fisher "points out that recognition that one has a set of thoughts does not imply that one is a particular thinker or another. …[T]he only claim that is indubitable here is the agent-independent claim that there is cognitive activity present."


title: Cogito, ergo sum

text: The objection, as presented by Georg Lichtenberg, is that rather than supposing an entity that is thinking, Descartes should have said: "thinking is occurring." That is, whatever the force of the "cogito", Descartes draws too much from it; the existence of a thinking thing, the reference of the "I," is more than the "cogito" can justify. Friedrich Nietzsche criticized the phrase in that it presupposes that there is an "I", that there is such an activity as "thinking", and that "I" know what "thinking" is. He suggested a more appropriate phrase would be "it thinks" wherein the "it" could be an impersonal subject as in the sentence "It is raining."


title: Cogito, ergo sum

text: The Danish philosopher Søren Kierkegaard calls the phrase a tautology in his "Concluding Unscientific Postscript". He argues that the "cogito" already presupposes the existence of "I", and therefore concluding with existence is logically trivial. Kierkegaard's argument can be made clearer if one extracts the premise "I think" into the premises "'x' thinks" and "I am that 'x'", where "x" is used as a placeholder in order to disambiguate the "I" from the thinking thing.


title: Cogito, ergo sum

text: Here, the "cogito" has already assumed the "I"'s existence as that which thinks. For Kierkegaard, Descartes is merely "developing the content of a concept", namely that the "I", which already exists, thinks. As Kierkegaard argues, the proper logical flow of argument is that existence is already assumed or presupposed in order for thinking to occur, not that existence is concluded from that thinking.


title: Cogito, ergo sum

text: Bernard Williams claims that what we are dealing with when we talk of thought, or when we say "I am thinking," is something conceivable from a third-person perspective—namely objective "thought-events" in the former case, and an objective thinker in the latter. He argues, first, that it is impossible to make sense of "there is thinking" without relativizing it to "something." However, this something cannot be Cartesian egos, because it is impossible to differentiate objectively between things just on the basis of the pure content of consciousness. The obvious problem is that, through introspection, or our experience of consciousness, we have no way of moving to conclude the existence of any third-personal fact, to conceive of which would require something above and beyond just the purely subjective contents of the mind.


title: Cogito, ergo sum

text: As a critic of Cartesian subjectivity, Heidegger sought to ground human subjectivity in death as that certainty which individualizes and authenticates our being. As he wrote in 1925 in "History of the Concept of Time":


title: Cogito, ergo sum

text: The Scottish philosopher John Macmurray rejects the "cogito" outright in order to place action at the center of a philosophical system he entitles the Form of the Personal. "We must reject this, both as standpoint and as method. If this be philosophy, then philosophy is a bubble floating in an atmosphere of unreality." The reliance on thought creates an irreconcilable dualism between thought and action in which the unity of experience is lost, thus dissolving the integrity of our selves, and destroying any connection with reality. In order to formulate a more adequate "cogito", Macmurray proposes the substitution of "I do" for "I think," ultimately leading to a belief in God as an agent to whom all persons stand in relation.


title: C data types

text: In the C programming language, data types constitute the semantics and characteristics of storage of data elements. They are expressed in the language syntax in form of declarations for memory locations or variables. Data types also determine the types of operations or methods of processing of data elements.


title: C data types

text: The C language provides basic arithmetic types, such as integer and real number types, and syntax to build array and compound types. "Headers" for the C standard library, to be used via include directives, contain definitions of support types, that have additional properties, such as providing storage with an exact size, independent of the language implementation on specific hardware platforms.


title: C data types

text: The C language provides the four basic arithmetic type specifiers "char", "int", "float" and "double", and the modifiers "signed", "unsigned", "short", and "long". The following table lists the permissible combinations in specifying a large set of storage size-specific declarations.


title: C data types

text: The actual size of the integer types varies by implementation. The standard requires only size relations between the data types and minimum sizes for each data type:


title: C data types

text: The relation requirements are that the codice_1 is not smaller than codice_2, which is not smaller than codice_3, which is not smaller than codice_4. As codice_5's size is always the minimum supported data type, no other data types (except bit-fields) can be smaller.


title: C data types

text: The minimum size for codice_5 is 8 bits, the minimum size for codice_4 and codice_3 is 16 bits, for codice_2 it is 32 bits and codice_1 must contain at least 64 bits.


title: C data types

text: The type codice_3 should be the integer type that the target processor is most efficiently working with. This allows great flexibility: for example, all types can be 64-bit. However, several different integer width schemes (data models) are popular. Because the data model defines how different programs communicate, a uniform data model is used within a given operating system application interface.


title: C data types

text: In practice, codice_5 is usually 8 bits in size and codice_4 is usually 16 bits in size (as are their unsigned counterparts). This holds true for platforms as diverse as 1990s SunOS 4 Unix, Microsoft MS-DOS, modern Linux, and Microchip MCC18 for embedded 8-bit PIC microcontrollers. POSIX requires codice_5 to be exactly 8 bits in size.


title: C data types

text: Various rules in the C standard make codice_15 the basic type used for arrays suitable to store arbitrary non-bit-field objects: its lack of padding bits and trap representations, the definition of "object representation", and the possibility of aliasing.


title: C data types

text: The actual size and behavior of floating-point types also vary by implementation. The only requirement is that codice_16 is not smaller than codice_17, which is not smaller than codice_18. Usually, the 32-bit and 64-bit IEEE 754 binary floating-point formats are used for codice_18 and codice_17 respectively.


title: C data types

text: The C99 standard includes new real floating-point types codice_21 and codice_22, defined in codice_23. They correspond to the types used for the intermediate results of floating-point expressions when codice_24 is 0, 1, or 2. These types may be wider than codice_16.


title: C data types

text: C99 added a boolean (true/false) type codice_29. Additionally, the codice_30 header defines codice_31 as a convenient alias for this type, and also provides macros for codice_32 and codice_33. codice_29 functions similarly to a normal integer type, with one exception: any assignments to a codice_29 that are not 0 (false) are stored as 1 (true). This behavior exists to avoid integer overflows in implicit narrowing conversions. For example, in the following code:


title: C data types

text: Variable codice_36 evaluates to false if codice_15 has a size of 8 bits. This is because the value 256 does not fit in the data type, which results in the lower 8 bits of it being used, resulting in a zero value. However, changing the type causes the previous code to behave normally:


title: C data types

text: The C language specification includes the s codice_38 and codice_39 to represent memory-related quantities. Their size is defined according to the target processor's arithmetic capabilities, not the memory capabilities, such as available address space. Both of these types are defined in the codice_40 header (codice_41 in C++).


title: C data types

text: codice_38 is an unsigned integer type used to represent the size of any object (including arrays) in the particular implementation. The operator yields a value of the type codice_38. The maximum size of codice_38 is provided via codice_45, a macro constant which is defined in the codice_46 header (codice_47 header in C++). codice_38 is guaranteed to be at least 16 bits wide. Additionally, POSIX includes codice_49, which is a signed integer type of the same width as codice_38.


title: C data types

text: codice_39 is a signed integer type used to represent the difference between pointers. It is guaranteed to be valid only against pointers of the same type; subtraction of pointers consisting of different types is implementation-defined.


title: C data types

text: Information about the actual properties, such as size, of the basic arithmetic types, is provided via macro constants in two headers: codice_52 header (codice_53 header in C++) defines macros for integer types and codice_54 header (codice_55 header in C++) defines macros for floating-point types. The actual values depend on the implementation.


title: C data types

text: The C99 standard includes definitions of several new integer types to enhance the portability of programs. The already available basic integer types were deemed insufficient, because their actual sizes are implementation defined and may vary across different systems. The new types are especially useful in embedded environments where hardware usually supports only several types and that support varies between different environments. All new types are defined in codice_114 header (codice_115 header in C++) and also are available at codice_46 header (codice_47 header in C++). The types can be grouped into the following categories:


title: C data types

text: The following table summarizes the types and the interface to acquire the implementation details ("n" refers to the number of bits):


title: C data types

text: The codice_114 header (codice_115 in C++) provides features that enhance the functionality of the types defined in the codice_46 header. It defines macros for printf format string and scanf format string specifiers corresponding to the types defined in codice_46 and several functions for working with the codice_122 and codice_123 types. This header was added in C99.


title: C data types

text: The macros are in the format codice_124. Here "{fmt}" defines the output formatting and is one of codice_125 (decimal), codice_126 (hexadecimal), codice_127 (octal), codice_128 (unsigned) and codice_129 (integer). "{type}" defines the type of the argument and is one of codice_130, codice_131, codice_132, codice_133, codice_134, where codice_130 corresponds to the number of bits in the argument.


title: C data types

text: The macros are in the format codice_136. Here "{fmt}" defines the output formatting and is one of codice_125 (decimal), codice_126 (hexadecimal), codice_127 (octal), codice_128 (unsigned) and codice_129 (integer). "{type}" defines the type of the argument and is one of codice_130, codice_131, codice_132, codice_133, codice_134, where codice_130 corresponds to the number of bits in the argument.


title: C data types

text: Similarly to the fixed-width integer types, ISO/IEC TS 18661 specifies floating-point types for IEEE 754 interchange and extended formats in binary and decimal:


title: C data types

text: Structures aggregate the storage of multiple data items, of potentially differing data types, into one memory block referenced by a single variable. The following example declares the data type codice_152 which contains the name and birthday of a person. The structure definition is followed by a declaration of the variable codice_153 that allocates the needed storage.


title: C data types

text: The memory layout of a structure is a language implementation issue for each platform, with a few restrictions. The memory address of the first member must be the same as the address of structure itself. Structures may be initialized or assigned to using compound literals. A function may directly return a structure, although this is often not efficient at run-time. Since C99, a structure may also end with a flexible array member.


title: C data types

text: A structure containing a pointer to a structure of its own type is commonly used to build linked data structures:


title: C data types

text: For every type codice_154, except void and function types, there exist the types ""array of codice_155 elements of type codice_154"". An array is a collection of values, all of the same type, stored contiguously in memory. An array of size codice_155 is indexed by integers from codice_158 up to and including codice_159. Here is a brief example:


title: C data types

text: Arrays can be initialized with a compound initializer, but not assigned. Arrays are passed to functions by passing a pointer to the first element. Multidimensional arrays are defined as ""array of array …"", and all except the outermost dimension must have compile-time constant size:


title: C data types

text: Every data type codice_154 has a corresponding type "pointer to codice_154". A pointer is a data type that contains the address of a storage location of a variable of a particular type. They are declared with the asterisk (codice_162) type declarator following the basic storage type and preceding the variable name. Whitespace before or after the asterisk is optional.


title: C data types

text: Pointers may also be declared for pointer data types, thus creating multiple indirect pointers, such as and , including pointers to array types. The latter are less common than an array of pointers, and their syntax may be confusing:


title: C data types

text: The element codice_163 requires ten blocks of memory of the size of "pointer to codice_5" (usually 40 or 80 bytes on common platforms), but element codice_165 is only one pointer (size 4 or 8 bytes), and the data it refers to is an array of ten bytes ().


title: C data types

text: A union type is a special construct that permits access to the same memory block by using a choice of differing type descriptions. For example, a union of data types may be declared to permit reading the same data either as an integer, a float, or any other user declared type:


title: C data types

text: The total size of codice_128 is the size of codice_167 – which happens to be the sum of the sizes of codice_168 and codice_169 – since codice_170 is larger than both codice_129 and codice_172. When assigning something to codice_173, some parts of codice_174 may be preserved if codice_173 is smaller than codice_174.


title: C data types

text: Reading from a union member is not the same as casting since the value of the member is not converted, but merely read.


title: C data types

text: Function pointers allow referencing functions with a particular signature. For example, to store the address of the standard function codice_177 in the variable codice_178:


title: C data types

text: Function pointers are invoked by name just like normal function calls. Function pointers are separate from pointers and void pointers.


title: C data types

text: The aforementioned types can be characterized further by type qualifiers, yielding a "qualified type". and C11, there are four type qualifiers in standard C: codice_179 (C89), codice_180 (C89), codice_181 (C99) and codice_182 (C11) the latter has a private name to avoid clashing with user names, but the more ordinary name codice_183 can be used if the codice_184 header is included. Of these, codice_179 is by far the best-known and most used, appearing in the standard library and encountered in any significant use of the C language, which must satisfy const-correctness. The other qualifiers are used for low-level programming, and while widely used there, are rarely used by typical programmers.


title: Tesla coil

text: A Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in 1891. It is used to produce high-voltage, low-current, high-frequency alternating-current electricity. Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits.


title: Tesla coil

text: Tesla used these circuits to conduct innovative experiments in electrical lighting, phosphorescence, X-ray generation, high-frequency alternating current phenomena, electrotherapy, and the transmission of electrical energy without wires. Tesla coil circuits were used commercially in spark-gap radio transmitters for wireless telegraphy until the 1920s, and in medical equipment such as electrotherapy and violet ray devices. Today, their main usage is for entertainment and educational displays, although small coils are still used as leak detectors for high-vacuum systems.


title: Tesla coil

text: Originally, Tesla coils used fixed spark gaps or rotary spark gaps to provide intermittent excitation of the resonant circuit; more recently, electronic devices are used to provide the switching action required.


title: Tesla coil

text: A Tesla coil is a radio frequency oscillator that drives an air-core double-tuned resonant transformer to produce high voltages at low currents. Tesla's original circuits as well as most modern coils use a simple spark gap to excite oscillations in the tuned transformer. More sophisticated designs use transistor or thyristor switches or vacuum tube electronic oscillators to drive the resonant transformer.


title: Tesla coil

text: Tesla coils can produce output voltages from 50 kilovolts to several million volts for large coils. The alternating current output is in the low radio frequency range, usually between 50 kHz and 1 MHz. Although some oscillator-driven coils generate a continuous alternating current, most Tesla coils have a pulsed output; the high voltage consists of a rapid string of pulses of radio frequency alternating current.


title: Tesla coil

text: The specialized transformer used in the Tesla coil circuit, called a resonant transformer, oscillation transformer, or radio-frequency (RF) transformer, functions differently from ordinary transformers used in AC power circuits. While an ordinary transformer is designed to "transfer" energy efficiently from primary to secondary winding, the resonant transformer is also designed to "temporarily store" electrical energy. Each winding has a capacitance across it and functions as an LC circuit (resonant circuit, tuned circuit), storing oscillating electrical energy, analogously to the way a tuning fork stores vibrational mechanical energy. The primary coil "(L1)" consisting of a relatively few turns of heavy copper wire or tubing, is connected to a capacitor "(C1)" through the spark gap "(SG)". The secondary coil "(L2)" consists of many turns (hundreds to thousands) of fine wire on a hollow cylindrical form inside the primary. The secondary is not connected to an actual capacitor, but it also functions as an LC circuit, the inductance of "(L2)" resonates with stray capacitance "(C2)", the sum of the stray parasitic capacitance between the windings of the coil, and the capacitance of the toroidal metal electrode attached to the high-voltage terminal. The primary and secondary circuits are tuned so that they have the same resonant frequency, so they exchange energy, acting like a coupled oscillator; during each spark the stored energy rapidly oscillates back and forth between the primary and secondary.


title: Tesla coil

text: The peculiar design of the coil is dictated by the need to achieve low resistive energy losses (high Q factor) at high frequencies, which results in the largest secondary voltages:


title: Tesla coil

text: The circuit operates in a rapidly repeating cycle in which the supply transformer "(T)" charges the primary capacitor "(C1)" up, which then discharges in a spark through the spark gap, creating a brief pulse of oscillating current in the primary circuit which excites a high oscillating voltage across the secondary:


title: Tesla coil

text: This entire cycle takes place very rapidly, the oscillations dying out in a time of the order of a millisecond. Each spark across the spark gap produces a pulse of damped sinusoidal high voltage at the output terminal of the coil. Each pulse dies out before the next spark occurs, so the coil generates a string of damped waves, not a continuous sinusoidal voltage. The high voltage from the supply transformer that charges the capacitor is a 50 or 60 Hz sine wave. Depending on how the spark gap is set, usually one or two sparks occur at the peak of each half-cycle of the mains current, so there are more than a hundred sparks per second. Thus the spark at the spark gap appears continuous, as do the high-voltage streamers from the top of the coil.


title: Tesla coil

text: The supply transformer "(T)" secondary winding is connected across the primary tuned circuit. It might seem that the transformer would be a leakage path for the RF current, damping the oscillations. However its large inductance gives it a very high impedance at the resonant frequency, so it acts as an open circuit to the oscillating current. If the supply transformer has inadequate short-circuit inductance, radio frequency chokes are placed in its secondary leads to block the RF current.


title: Tesla coil

text: To produce the largest output voltage, the primary and secondary tuned circuits are adjusted to resonance with each other. The resonant frequencies of the primary and secondary circuits, formula_1 and formula_2, are determined by the inductance and capacitance in each circuit:


title: Tesla coil

text: Generally the secondary is not adjustable, so the primary circuit is tuned, usually by a moveable tap on the primary coil L, until it resonates at the same frequency as the secondary:


title: Tesla coil

text: The resonant frequency of Tesla coils is in the low radio frequency (RF) range, usually between 50 kHz and 1 MHz. However, because of the impulsive nature of the spark they produce broadband radio noise, and without shielding can be a significant source of RFI, interfering with nearby radio and television reception.


title: Tesla coil

text: In a resonant transformer the high voltage is produced by resonance; the output voltage is not proportional to the turns ratio, as in an ordinary transformer. It can be calculated approximately from conservation of energy. At the beginning of the cycle, when the spark starts, all of the energy in the primary circuit formula_6 is stored in the primary capacitor formula_7. If formula_8 is the voltage at which the spark gap breaks down, which is usually close to the peak output voltage of the supply transformer "T", this energy is


title: Tesla coil

text: During the "ring up" this energy is transferred to the secondary circuit. Although some is lost as heat in the spark and other resistances, in modern coils, over 85% of the energy ends up in the secondary. At the peak (formula_10) of the secondary sinusoidal voltage waveform, all the energy in the secondary formula_11 is stored in the capacitance formula_12 between the ends of the secondary coil


title: Tesla coil

text: Assuming no energy losses, formula_14. Substituting into this equation and simplifying, the peak secondary voltage is


title: Tesla coil

text: The second formula above is derived from the first using the resonance condition formula_15. Since the capacitance of the secondary coil is very small compared to the primary capacitor, the primary voltage is stepped up to a high value.


title: Tesla coil

text: The above peak voltage is only achieved in coils in which air discharges do not occur; in coils which produce sparks, like entertainment coils, the peak voltage on the terminal is limited to the voltage at which the air breaks down and becomes conductive. As the output voltage increases during each voltage pulse, it reaches the point where the air next to the high-voltage terminal ionizes and corona, brush discharges, and streamer arcs break out from the terminal. This happens when the electric field strength exceeds the dielectric strength of the air, about 30 kV per centimeter. Since the electric field is greatest at sharp points and edges, air discharges start at these points on the high-voltage terminal. The voltage on the high-voltage terminal cannot increase above the air breakdown voltage, because additional electric charge pumped into the terminal from the secondary winding just escapes into the air. The output voltage of open-air Tesla coils is limited to a few million volts by air breakdown, but higher voltages can be achieved by coils immersed in pressurized tanks of insulating oil.


title: Tesla coil

text: Most Tesla coil designs have a smooth spherical- or toroidal-shaped metal electrode on the high-voltage terminal. The electrode serves as one plate of a capacitor, with the Earth as the other plate, forming the tuned circuit with the secondary winding. Although the "toroid" increases the secondary capacitance, which tends to reduce the peak voltage, its main effect is that its large-diameter curved surface reduces the potential gradient (electric field) at the high-voltage terminal; it functions similarly to a corona ring, increasing the voltage threshold at which air discharges such as corona and brush discharges occur. Suppressing premature air breakdown and energy loss allows the voltage to build to higher values on the peaks of the waveform, creating longer, more spectacular streamers when air discharges finally occur.


title: Tesla coil

text: If the top electrode is large and smooth enough, the electric field at its surface may never get high enough even at the peak voltage to cause air breakdown, and air discharges will not occur. Some entertainment coils have a sharp "spark point" projecting from the torus to start discharges.


title: Tesla coil

text: Tesla coil circuits can be classified by the type of "excitation" they use, what type of circuit is used to apply current to the primary winding of the resonant transformer:


title: Tesla coil

text: Electrical oscillation and resonant air-core transformer circuits had been explored before Tesla. Resonant circuits using Leyden jars were invented beginning in 1826 by Felix Savary, Joseph Henry, William Thomson, and Oliver Lodge. and Henry Rowland built a resonant transformer in 1889. Elihu Thomson invented the Tesla coil circuit independently at the same time Tesla did. Tesla patented his Tesla coil circuit April 25, 1891. and first publicly demonstrated it May 20, 1891, in his lecture ""Experiments with Alternate Currents of Very High Frequency and Their Application to Methods of Artificial Illumination"" before the American Institute of Electrical Engineers at Columbia College, New York. Although Tesla patented many similar circuits during this period, this was the first that contained all the elements of the Tesla coil: high-voltage primary transformer, capacitor, spark gap, and air core "oscillation transformer".


title: Tesla coil

text: Modern high-voltage enthusiasts usually build Tesla coils similar to some of Tesla's "later" 2-coil air-core designs. These typically consist of a primary tank circuit, a series LC (inductance-capacitance) circuit composed of a high-voltage capacitor, spark gap, and primary coil; and the secondary LC circuit, a series-resonant circuit consisting of the secondary coil plus a terminal capacitance or "top load". In Tesla's more advanced (magnifier) design, a third coil is added. The secondary LC circuit is composed of a tightly coupled air-core transformer secondary coil driving the bottom of a separate third coil helical resonator. Modern 2-coil systems use a single secondary coil. The top of the secondary is then connected to a topload terminal, which forms one 'plate' of a capacitor, the other 'plate' being the earth (or "ground"). The primary LC circuit is tuned so that it resonates at the same frequency as the secondary LC circuit. The primary and secondary coils are magnetically coupled, creating a dual-tuned resonant air-core transformer. Earlier oil-insulated Tesla coils needed large and long insulators at their high-voltage terminals to prevent discharge in air. Later Tesla coils spread their electric fields over larger distances to prevent high electrical stresses in the first place, thereby allowing operation in free air. Most modern Tesla coils also use toroid-shaped output terminals. These are often fabricated from spun metal or flexible aluminum ducting. The toroidal shape helps to control the high electric field near the top of the secondary by directing sparks outward and away from the primary and secondary windings.


title: Tesla coil

text: A more complex version of a Tesla coil, termed a "magnifier" by Tesla, uses a more tightly coupled air-core resonance "driver" transformer (or "master oscillator") and a smaller, remotely located output coil (called the "extra coil" or simply the resonator) that has a large number of turns on a relatively small coil form. The bottom of the driver's secondary winding is connected to ground. The opposite end is connected to the bottom of the extra coil through an insulated conductor that is sometimes called the transmission line. Since the transmission line operates at relatively high RF voltages, it is typically made of 1" diameter metal tubing to reduce corona losses. Since the third coil is located some distance away from the driver, it is not magnetically coupled to it. RF energy is instead directly coupled from the output of the driver into the bottom of the third coil, causing it to "ring up" to very high voltages. The combination of the two-coil driver and third coil resonator adds another degree of freedom to the system, making tuning considerably more complex than that of a 2-coil system. The transient response for multiple resonance networks (of which the Tesla magnifier is a sub-set) has only recently been solved. It is now known that a variety of useful tuning "modes" are available, and in most operating modes the extra coil will ring at a different frequency than the master oscillator.


title: Tesla coil

text: Modern transistor or vacuum tube Tesla coils do not use a primary spark gap. Instead, the transistor(s) or vacuum tube(s) provide the switching or amplifying function necessary to generate RF power for the primary circuit. Solid-state Tesla coils use the lowest primary operating voltage, typically between 155 and 800 volts, and drive the primary winding using either a single, half-bridge, or full-bridge arrangement of transistors, MOSFETs, or IGBTs to switch the primary current. Vacuum tube coils typically operate with plate voltages between 1500 and 6000 volts, while most spark gap coils operate with primary voltages of 6,000 to 25,000 volts. The primary winding of a traditional transistor Tesla coil is wound around only the bottom portion of the secondary coil. This configuration illustrates operation of the secondary as a pumped resonator. The primary 'induces' alternating voltage into the bottom-most portion of the secondary, providing regular 'pushes' (similar to providing properly timed pushes to a playground swing). Additional energy is transferred from the primary to the secondary inductance and top-load capacitance during each "push", and secondary output voltage builds (called 'ring-up'). An electronic feedback circuit is usually used to adaptively synchronize the primary oscillator to the growing resonance in the secondary, and this is the only tuning consideration beyond the initial choice of a reasonable top-load.


title: Tesla coil

text: In a dual resonant solid-state Tesla coil (DRSSTC), the electronic switching of the solid-state Tesla coil is combined with the resonant primary circuit of a spark-gap Tesla coil. The resonant primary circuit is formed by connecting a capacitor in series with the primary winding of the coil, so that the combination forms a series tank circuit with a resonant frequency near that of the secondary circuit. Because of the additional resonant circuit, one manual and one adaptive tuning adjustment are necessary. Also, an interrupter is usually used to reduce the duty cycle of the switching bridge, to improve peak power capabilities; similarly, IGBTs are more popular in this application than bipolar junction transistors or MOSFETs, due to their superior power handling characteristics. A current-limiting circuit is usually used to limit maximum primary tank current (which must be switched by the IGBT's) to a safe level. Performance of a DRSSTC can be comparable to a medium-power spark-gap Tesla coil, and efficiency (as measured by spark length versus input power) can be significantly greater than a spark-gap Tesla coil operating at the same input power.


title: Tesla coil

text: A large Tesla coil of more modern design often operates at very high peak power levels, up to many megawatts (millions of watts, equivalent to thousands of horsepower). It is therefore adjusted and operated carefully, not only for efficiency and economy, but also for safety. If, due to improper tuning, the maximum voltage point occurs below the terminal, along the secondary coil, a discharge (spark) may break out and damage or destroy the coil wire, supports, or nearby objects.


title: Tesla coil

text: Tesla experimented with these, and many other, circuit configurations (see right). The Tesla coil primary winding, spark gap and tank capacitor are connected in series. In each circuit, the AC supply transformer charges the tank capacitor until its voltage is sufficient to break down the spark gap. The gap suddenly fires, allowing the charged tank capacitor to discharge into the primary winding. Once the gap fires, the electrical behavior of either circuit is identical. Experiments have shown that neither circuit offers any marked performance advantage over the other.


title: Tesla coil

text: However, in the typical circuit, the spark gap's short circuiting action prevents high-frequency oscillations from 'backing up' into the supply transformer. In the alternate circuit, high amplitude high-frequency oscillations that appear across the capacitor also are applied to the supply transformer's winding. This can induce corona discharges between turns that weaken and eventually destroy the transformer's insulation. Experienced Tesla coil builders almost exclusively use the top circuit, often augmenting it with low pass filters (resistor and capacitor (RC) networks) between the supply transformer and spark gap to help protect the supply transformer. This is especially important when using transformers with fragile high-voltage windings, such as neon sign transformers (NSTs). Regardless of which configuration is used, the HV transformer must be of a type that self-limits its secondary current by means of internal short-circuit inductance. A normal (low Short-circuit inductance) high-voltage transformer must use an external limiter (sometimes called a ballast) to limit current. NSTs are designed to have high Short-circuit inductance to limit their short circuit current to a safe level.


title: Tesla coil

text: The primary coil's resonant frequency is tuned to that of the secondary, by using low-power oscillations, then increasing the power (and retuning if necessary) until the system operates properly at maximum power. While tuning, a small projection (called a "breakout bump") is often added to the top terminal in order to stimulate corona and spark discharges (sometimes called streamers) into the surrounding air. Tuning can then be adjusted so as to achieve the longest streamers at a given power level, corresponding to a frequency match between the primary and secondary coil. Capacitive "loading" by the streamers tends to lower the resonant frequency of a Tesla coil operating under full power. A toroidal topload is often preferred to other shapes, such as a sphere. A toroid with a major diameter that is much larger than the secondary diameter provides improved shaping of the electric field at the topload. This provides better protection of the secondary winding (from damaging streamer strikes) than a sphere of similar diameter. And, a toroid permits fairly independent control of topload capacitance versus spark breakout voltage. A toroid's capacitance is mainly a function of its major diameter, while the spark breakout voltage is mainly a function of its minor diameter. A grid dip oscillator (GDO) is sometimes used to help facilitate initial tuning and aid in design. The resonant frequency of the secondary can be difficult to determine except by using a GDO or other experimental method, whereas the physical properties of the primary more closely represent lumped approximations of RF tank design. In this schema the secondary is built somewhat arbitrarily in imitation of other successful designs, or entirely so with supplies on hand, its resonant frequency is measured and the primary designed to suit.


title: Tesla coil

text: In coils that produce air discharges, such as those built for entertainment, electrical energy from the secondary and toroid is transferred to the surrounding air as electrical charge, heat, light, and sound. The process is similar to charging or discharging a capacitor, except that a Tesla coil uses AC instead of DC. The current that arises from shifting charges within a capacitor is called a displacement current. Tesla coil discharges are formed as a result of displacement currents as pulses of electrical charge are rapidly transferred between the high-voltage toroid and nearby regions within the air (called space charge regions). Although the space charge regions around the toroid are invisible, they play a profound role in the appearance and location of Tesla coil discharges.


title: Tesla coil

text: When the spark gap fires, the charged capacitor discharges into the primary winding, causing the primary circuit to oscillate. The oscillating primary current creates an oscillating magnetic field that couples to the secondary winding, transferring energy into the secondary side of the transformer and causing it to oscillate with the toroid capacitance to ground. Energy transfer occurs over a number of cycles, until most of the energy that was originally in the primary side is transferred to the secondary side. The greater the magnetic coupling between windings, the shorter the time required to complete the energy transfer. As energy builds within the oscillating secondary circuit, the amplitude of the toroid's RF voltage rapidly increases, and the air surrounding the toroid begins to undergo dielectric breakdown, forming a corona discharge.


title: Tesla coil

text: As the secondary coil's energy (and output voltage) continue to increase, larger pulses of displacement current further ionize and heat the air at the point of initial breakdown. This forms a very electrically conductive "root" of hotter plasma, called a leader, that projects outward from the toroid. The plasma within the leader is considerably hotter than a corona discharge, and is considerably more conductive. In fact, its properties are similar to an electric arc. The leader tapers and branches into thousands of thinner, cooler, hair-like discharges (called streamers). The streamers look like a bluish 'haze' at the ends of the more luminous leaders. The streamers transfer charge between the leaders and toroid to nearby space charge regions. The displacement currents from countless streamers all feed into the leader, helping to keep it hot and electrically conductive.


title: Tesla coil

text: The primary break rate of sparking Tesla coils is slow compared to the resonant frequency of the resonator-topload assembly. When the switch closes, energy is transferred from the primary LC circuit to the resonator where the voltage rings up over a short period of time up culminating in the electrical discharge. In a spark gap Tesla coil, the primary-to-secondary energy transfer process happens repetitively at typical pulsing rates of 50–500 times per second, depending on the frequency of the input line voltage. At these rates, previously-formed leader channels do not get a chance to fully cool down between pulses. So, on successive pulses, newer discharges can build upon the hot pathways left by their predecessors. This causes incremental growth of the leader from one pulse to the next, lengthening the entire discharge on each successive pulse. Repetitive pulsing causes the discharges to grow until the average energy available from the Tesla coil during each pulse balances the average energy being lost in the discharges (mostly as heat). At this point, dynamic equilibrium is reached, and the discharges have reached their maximum length for the Tesla coil's output power level. The unique combination of a rising high-voltage radio frequency envelope and repetitive pulsing seem to be ideally suited to creating long, branching discharges that are considerably longer than would be otherwise expected by output voltage considerations alone. High-voltage, low-energy discharges create filamentary multibranched discharges which are purplish-blue in colour. High-voltage, high-energy discharges create thicker discharges with fewer branches, are pale and luminous, almost white, and are much longer than low-energy discharges, because of increased ionisation. A strong smell of ozone and nitrogen oxides will occur in the area. The important factors for maximum discharge length appear to be voltage, energy, and still air of low to moderate humidity. There are comparatively few scientific studies about the initiation and growth of pulsed lower-frequency RF discharges, so some aspects of Tesla coil air discharges are not as well understood when compared to DC, power-frequency AC, HV impulse, and lightning discharges.


title: Tesla coil

text: Today, although small Tesla coils are used as leak detectors in scientific high-vacuum systems and igniters in arc welders, their main use is entertainment and educational displays.


title: Tesla coil

text: Tesla coils are displayed as attractions at science museums and electronics fairs, and are used to demonstrate principles of high-frequency electricity in science classes in schools and colleges.


title: Tesla coil

text: Since they are simple enough for an amateur to make, Tesla coils are a popular student science fair project, and are homemade by a large worldwide community of hobbyists. Builders of Tesla coils as a hobby are called "coilers". They attend "coiling" conventions where they display their home-made Tesla coils and other high-voltage devices. Low-power Tesla coils are also sometimes used as a high-voltage source for Kirlian photography.


title: Tesla coil

text: The current world's largest Tesla coil is a 130,000-watt unit built by Greg Leyh and Eric Orr, part of a sculpture titled "Electrum" owned by Alan Gibbs and currently residing in a private sculpture park at Kakanui Point near Auckland, New Zealand. Another very large Tesla coil, designed and built by Syd Klinge, is shown every year at the Coachella Valley Music and Arts Festival in Coachella, California.


title: Tesla coil

text: Tesla coils can also be used to generate sounds, including music, by modulating the system's effective "break rate" (i.e., the rate and duration of high power RF bursts) via MIDI data and a control unit. The actual MIDI data is interpreted by a microcontroller which converts the MIDI data into a PWM output which can be sent to the Tesla coil via a fiber optic interface.An extensive outdoor musical concert has demonstrated using Tesla coils during the Engineering Open House (EOH) at the University of Illinois Urbana-Champaign. The Icelandic artist Björk used a Tesla coil in her song "Thunderbolt" as the main instrument in the song. The musical group ArcAttack uses modulated Tesla coils and a man in a chain-link suit to play music.


title: Tesla coil

text: Scientists working with high-vacuum systems test for the presence of tiny pin holes in the apparatus (especially a newly blown piece of glassware) using high-voltage discharges produced by a small handheld Tesla coil. When the system is evacuated the high-voltage electrode of the coil is played over the outside of the apparatus. At low pressures, air is more easily ionized and thus conducts electricity better than atmospheric-pressure air. Therefore, the discharge travels through any pin hole immediately below it, producing a corona discharge inside the evacuated space which illuminates the hole, indicating points that need to be annealed or reblown before they can be used in an experiment.


title: Tesla coil

text: In 2016, Rice University scientists used the field of a Tesla coil to remotely align tiny carbon nanotubes into a circuit, a process they dubbed "teslaphoresis".


title: Tesla coil

text: The high-voltage radio frequency (RF) discharges from the output terminal of a Tesla coil pose a unique hazard not found in other high-voltage equipment: when passed through the body they often do not cause the painful sensation and muscle contraction of electric shock, as lower frequency AC or DC currents do. The nervous system is insensitive to currents with frequencies over 10 – 20 kHz. It is thought that the reason for this is that a certain minimum number of ions must be driven across a nerve cell's membrane by the imposed voltage to trigger the nerve cell to depolarize and transmit an impulse. At radio frequencies, there is insufficient time during a half-cycle for enough ions to cross the membrane before the alternating voltage reverses. The danger is that since no pain is felt, experimenters often assume the currents are harmless. Teachers and hobbyists demonstrating small Tesla coils often impress their audience by touching the high-voltage terminal or allowing the streamer arcs to pass through their body.


title: Tesla coil

text: If the arcs from the high-voltage terminal strike the bare skin, they can cause deep-seated burns called "RF burns". This is often avoided by allowing the arcs to strike a piece of metal held in the hand, or a thimble on a finger, instead. The current passes from the metal into the person's hand through a wide enough surface area to avoid causing burns. Often no sensation is felt, or just a warmth or tingling.


title: Tesla coil

text: However this does not mean the current is harmless. Even a small Tesla coil produces many times the electrical energy necessary to stop the heart, if the frequency happens to be low enough to cause ventricular fibrillation. A minor misadjustment of the coil could result in electrocution. In addition, the RF current heats the tissues it passes through. Carefully controlled Tesla coil currents, applied directly to the skin by electrodes, were used in the early 20th century for deep body tissue heating in the medical field of longwave "diathermy". The amount of heating depends on the current density, which depends on the power output of the Tesla coil and the cross-sectional area of the path the current takes through the body to ground. Particularly if it passes through narrow structures such as blood vessels or joints it may raise the local tissue temperature to hyperthermic levels, "cooking" internal organs or causing other injuries. International ICNIRP safety standards for RF current in the body in the Tesla coil frequency range of 0.1 – 1 MHz specify a maximum current density of 0.2 mA per square centimeter and a maximum power absorption rate (SAR) in tissue of 4 W/kg in limbs and 0.8 W/kg average over the body. Even low power Tesla coils could exceed these limits, and it is generally impossible to determine the threshold current where bodily injury begins. Being struck by arcs from a high power (> 1000 watt) Tesla coil is likely to be fatal.


title: Tesla coil

text: Another reported hazard of this practice is that arcs from the high-voltage terminal often strike the primary winding of the coil. This momentarily creates a conductive path for the lethal 50/60 Hz primary current from the supply transformer to reach the output terminal. If a person is connected to the output terminal at the time, either by touching it or allowing arcs from the terminal to strike the person's body, then the high primary current could pass through the conductive ionized air path, through the body to ground, causing electrocution.


title: Tesla coil

text: An erroneous explanation for the absence of electric shock that has persisted among Tesla coil hobbyists is that the high-frequency currents travel through the body close to the surface, and thus do not penetrate to vital organs or nerves, due to an electromagnetic phenomenon called "skin effect".


title: Tesla coil

text: This theory is false. RF current does tend to flow on the surface of conductors due to skin effect, but the depth to which it penetrates, called "skin depth", depends on the resistivity and permeability of the material as well as the frequency. Although skin effect limits currents of Tesla coil frequencies to the outer fraction of a millimeter in metal conductors, the skin depth of the current in body tissue is much deeper due to its higher resistivity. The depth of penetration of currents of Tesla frequency (0.1 – 1 MHz) in human tissues is roughly 24 to 72 centimeters (9 to 28 inches). Since even the deepest tissues are closer than this to the surface, skin effect has little influence on the path of the current through the body; it tends to take the path of minimum electrical impedance to ground, and can easily pass through the core of the body. In the medical therapy called longwave diathermy, carefully controlled RF current of Tesla frequencies was used for decades for deep tissue warming, including heating internal organs such as the lungs. Modern shortwave diathermy machines use a higher frequency of 27 MHz, which would have a correspondingly smaller skin depth, yet these frequencies are still able to penetrate deep body tissues.


title: Nicole Ari Parker

text: Nicole Ari Parker Kodjoe (born October 7, 1970) is an American actress and model. She made her screen debut with a leading role in the critically acclaimed independent film "The Incredibly True Adventure of Two Girls in Love" (1995) and went on to appear in "Boogie Nights" (1997), directed by Paul Thomas Anderson.


title: Nicole Ari Parker

text: Parker has starred in a number of movies, including "Blue Streak" (1999), "Remember the Titans" (2000), "Brown Sugar" (2002), "Welcome Home Roscoe Jenkins" (2008), "Black Dynamite" (2009), and "Almost Christmas" (2016). On television, Parker played the leading role of attorney Teri Joseph (later Carter) in the Showtime drama series "Soul Food" (2000–04), for which she received five NAACP Image Award for Outstanding Actress in a Drama Series nominations. She also starred in the short-lived UPN romantic comedy "Second Time Around" (2004–05) and the ABC drama "Time After Time" (2017). In 2017, she joined the cast of Fox's prime-time soap opera "Empire" playing Giselle Barker. She formerly appeared as a recurring character in "Chicago P.D." as Deputy Superintendent Samantha Miller and in "And Just Like That..." as Lisa Todd Wexley.


title: Nicole Ari Parker

text: Parker was born in Baltimore, Maryland on October 7, 1970. She is the only child of her divorced parents, health care professional Susan Parker and dentist Donald Parker. After briefly attending a Montessori school, Parker entered Roland Park Country School, where she stayed through high school. At the age of 17, she won Best Actress in the state of Maryland's high school theater competition. She became a member of The Washington Ballet Company before earning an acting degree in 1993 from New York University's Tisch School of the Arts.


title: Nicole Ari Parker

text: Parker made her screen debut playing secondary role in the 1993 made-for-television movie "Other Women's Children" starring Melanie Mayron. Two years later she went to star in the critically acclaimed independent comedy-drama film, "The Incredibly True Adventure of Two Girls in Love". Also that year, she starred in the "Divas", a made-for-television musical drama film about female singing group. In 1997, she starred in the comedy-drama film "Boogie Nights" written and directed by Paul Thomas Anderson. The following year, she appeared in the television film "". Her other film credits include "The End of Violence" (1997), "Spark" (1998), the 1999 Sundance Film Festival winner "The Adventures of Sebastian Cole" (1998), "200 Cigarettes" (1999), "Loving Jezebel" (1999), "A Map of the World" (1999) and "Blue Streak" (1999).


title: Nicole Ari Parker

text: In 2000, Parker played the leading role in the drama film "Dancing in September" and starred opposite Denzel Washington in the biographical film "Remember the Titans", receiving NAACP Image Award for Outstanding Supporting Actress in a Motion Picture nomination. Also that year, she began starring as Teri Joseph in the Showtime drama series, "Soul Food". The series was an adaptation of George Tillman's 1997 drama film, "Soul Food", and the role of Teri played Vanessa Williams. The series ended in 2004. For her performance she received five NAACP Image Award for Outstanding Actress in a Drama Series nominations. She returned to film, starring in the 2002 romantic comedy "Brown Sugar". She later appeared in "King's Ransom" (2005), "Welcome Home Roscoe Jenkins" (2008) alongside her "Blue Streak" co-star Martin Lawrence, "Black Dynamite" (2009), "Imagine That" (2009), and "Pastor Brown" (2009).


title: Nicole Ari Parker

text: On television, Parker starred on the short-lived UPN sitcom, "Second Time Around" from 2004 to 2005. In 2010, she returned to television with starring role in the ABC legal drama, "The Deep End", the series was cancelled after one season. In 2012. she made her Broadway debut playing the role of Blanche DuBois in "A Streetcar Named Desire". In 2013, Parker was lead actress in the NBC drama pilot "Secret Lives of Husbands and Wives", and later had a recurring role on "Revolution". In 2014, she starred as a series regular in the first season of the TNT crime drama "Murder in the First", opposite Taye Diggs and Kathleen Robertson. In 2016, she appeared alongside Kimberly Elise and Mo'Nique in the comedy-drama film "Almost Christmas". In 2017, she starred in the another short-lived drama series, "Time After Time".


title: Nicole Ari Parker

text: In 2017, Parker joined the cast of Fox prime time soap opera, "Empire", playing Giselle Barker in a recurring role during the fourth season. She was promoted to a series regular for the fifth season, starring to series finale in 2020. For the 2020-21 television season, Parker had a recurring role on the NBC series, "Chicago P.D", and in late 2021 began starring in the HBO Max comedy-drama series, "And Just Like That..." playing the role of Lisa Todd Wexley.


title: Nicole Ari Parker

text: Parker eloped with actor Joseph Falasca in March 2001. Their marriage lasted only eight months; they divorced later that year. She married her "Soul Food" co-star Boris Kodjoe on May 21, 2005, in Gundelfingen, Germany. She gave birth to their first child, Sophie, on March 5, 2005. Sophie has spina bifida, which was diagnosed at birth. Parker gave birth to their son Nicolas in October 2006 in Atlanta, Georgia.


title: Iron Maiden discography

text: The discography of Iron Maiden, an English heavy metal band founded in 1975 by bassist Steve Harris, includes seventeen studio albums, as well as numerous live albums, compilations, EPs, singles, video albums, music videos, and box sets. After several personnel changes, they released their self-titled debut album in 1980 with vocalist Paul Di'Anno, guitarists Dave Murray and Dennis Stratton, and drummer Clive Burr, quickly becoming one of the leading proponents of the new wave of British heavy metal movement.


title: Iron Maiden discography

text: Guitarist Adrian Smith replaced Stratton, and "Killers" was released in 1981. Later that year, vocalist Bruce Dickinson replaced Paul Di'Anno, marking the beginning of a series of top-ten high-impact releases. They issued "The Number of the Beast", becoming the band's first release to top the UK charts, and received a platinum certification by the Recording Industry Association of America. Drummer Nicko McBrain replaced Clive Burr, and the band released "Piece of Mind" in 1983, followed by "Powerslave" (1984). Iron Maiden broadened their sound with the use of guitar synthesisers in "Somewhere in Time" (1986). Their following concept album, "Seventh Son of a Seventh Son", was released in 1988, and also topped the UK charts.


title: Iron Maiden discography

text: The line-up remained unchanged until Adrian Smith left the band during the pre-production stage of their last gold-certified album in the US, "No Prayer for the Dying" (1990); he was replaced by Janick Gers. Their next UK No. 1 album, "Fear of the Dark", was released in 1992, after which Dickinson left the band in the following year. His replacement, Blaze Bayley, debuted in 1995 with "The X Factor", an album that marked a decline in the band's career. The diminished fan interest in 1998 with "Virtual XI" prompted Bayley's departure.


title: Iron Maiden discography

text: Dickinson and Smith returned to the band in 1999, and a new album, "Brave New World", was issued in 2000. Three years later, "Dance of Death" was released. In 2006 they released "A Matter of Life and Death", which received, along with their two previous studio releases, a gold certification by the BPI. In 2010, Iron Maiden issued "The Final Frontier", which was positively received by critics, and debuted at No. 1 in over twenty-eight countries, including the United Kingdom. Their sixteenth studio effort, "The Book of Souls", was released on 4 September 2015 and became their fifth UK No. 1 album. Iron Maiden are considered one of the most influential and successful heavy metal bands in history, with "The Sunday Times" reporting in 2017 that the band have sold well over 100 million copies of their albums worldwide, despite little radio or television support. As of 2022 Iron Maiden have sold over 130 mln copies of their albums worldwide. According to "MD Daily Record" by 2021 all audio-visual catalogue of the band has sold in over 200 million copies worldwide, including regular albums, singles, VHS’, DVDs and all compilations. By 2022 their releases have been certified silver, gold and platinum around 600 times worldwide.


title: Friday the 13th (2009 film)

text: Friday the 13th is a 2009 American slasher film directed by Marcus Nispel, written by Damian Shannon and Mark Swift from a screen story by Shannon, Swift and Mark Wheaton. It is a reboot of the "Friday the 13th" franchise, which began in 1980, and is the twelfth installment. Nispel also directed the 2003 remake of Tobe Hooper's "The Texas Chain Saw Massacre" (1974), while Shannon and Swift wrote the screenplay for the 2003 crossover "Freddy vs. Jason". The film was produced by Platinum Dunes and Crystal Lake Entertainment and distributed by New Line Cinema and Paramount Pictures. It stars Jared Padalecki, Danielle Panabaker, Aaron Yoo, Amanda Righetti, Travis Van Winkle, and Derek Mears and follows Clay Miller (Padalecki) as he searches for his missing sister, Whitney (Righetti), who is captured by Jason Voorhees (Mears) while camping in woodland at Crystal Lake.


title: Friday the 13th (2009 film)

text: The film was originally conceived as an origin story, but the project evolved into a re-imagining of the first four "Friday the 13th" films. The character Jason Voorhees was redesigned as a lean, quick killer with a backstory that allows the viewer to feel sympathy for him, but not enough that he would lose his menace. In keeping with the tone of the film, Jason's mask was recreated from a mold of the original mask used for "Part III"; though there were subtle changes. "Friday the 13th" includes some of Harry Manfredini's musical score from the previous "Friday the 13th" films because the producers recognized its iconic status.


title: Friday the 13th (2009 film)

text: "Friday the 13th" was theatrically released in the United States on February 13, 2009, by New Line Cinema in North American territories and by Paramount Pictures internationally. The film received generally negative reviews from critics, who felt that it did not add anything new to the franchise. The film would go on to gross $92.7 million at the box office on a budget of $19 million, becoming the second-highest-grossing film in the franchise after "Freddy vs. Jason".


title: Friday the 13th (2009 film)

text: On June 13, 1980, a young Jason Voorhees watches as his mother Pamela is beheaded by a camp counselor, who was trying to escape Mrs. Voorhees's murder spree around Camp Crystal Lake. Almost thirty years later, five friendsWade, Richie, his girlfriend Amanda, Mike, and his girlfriend Whitneyarrive for a camping trip at Crystal Lake, where they hope to find a crop of marijuana growing in the woods. That night, an adult Jason kills everyone except Whitney, whom he captures as she resembles his mother at a young age.


title: Friday the 13th (2009 film)

text: Six weeks later, Trent, his girlfriend Jenna and friends Chelsea, Bree, Chewie, Nolan, and Lawrence arrive at Trent's summer cabin on the shore of Crystal Lake. Meanwhile, Whitney's brother Clay Miller arrives at the lake to search for her, despite his local sherrif's pleas to look elsewhere. Clay visits Trent's cabin, and Jenna agrees to help him search for Whitney. Chelsea and Nolan go wakeboarding on the lake where Jason kills Nolan with an arrow, and fatally stabs Chelsea with a machete. Meanwhile, Clay and Jenna search the old Crystal Lake campgrounds, where they see Jason hauling a body into the abandoned camp house.


title: Friday the 13th (2009 film)

text: Jenna and Clay run back to the cabin to warn the others about Jason. Chewie is killed by Jason in a tool shed near the cabin, while Trent and Bree have sex in a bedroom. Jenna and Clay arrive, and Clay calls the police. Jason then disconnects the cabin's electricity. Lawrence heads outside to search for Chewie, and Jason kills him with an axe. Jason then sneaks inside and kills Bree. A police officer arrives and knocks on the front door, but is killed by Jason before he can enter. Trent, Clay, and Jenna escape the cabin and become separated, and Trent is killed by Jason when he reaches the main road.


title: Friday the 13th (2009 film)

text: Jason chases Clay and Jenna back to the campgrounds, where Clay discovers Jason's lair and finds his sister underground, chained to a wall. Clay frees Whitney, and all three try to escape as Jason arrives. They find an exit, but Jenna is impaled by Jason's machete before she can escape. Jason corners Clay and Whitney in a barn, and Whitney confuses Jason by pretending to be Pamela. Clay and Whitney subdue Jason with a length of chain, and Whitney stabs Jason in the chest with his own machete. After sunrise, Clay and Whitney dump Jason's body into the lake, but before they leave, Jason bursts through the wooden dock and grabs Whitney.


title: Friday the 13th (2009 film)

text: New Line Cinema's Toby Emmerich approached Platinum Dunes producers Michael Bay, Brad Fuller and Andrew Form about remaking "Friday the 13th" in the same way they restarted "The Texas Chainsaw Massacre" franchise. They agreed and spent over a year obtaining the film rights from Paramount Pictures, New Line and Crystal Lake Entertainmentthe latter run by "Friday the 13th" creator Sean S. Cunningham. Paramount executives gave Platinum Dunes producers a license to use anything from the original films, including the title. Paramount was given the rights to distribute the film internationally and New Line retained U.S. distribution rights. Fuller and Form said they did not want to make "Friday the 13th Part 11" or "12", but wanted to rework the mythology. They liked elements from the first four filmssuch as plot points and ways particular characters are killedand planned to use these in their remake, which they did with Paramount's approval. Fuller said, "I think there are moments we want to address, like how does the hockey mask happen. It'll happen differently in our movie than in the third one. Where is Jason from, why do these killings happen, and what is Crystal Lake?" The producers initially expressed an interest in using Tommy Jarvis, a recurring character who first appeared in "", but the idea was scrapped.


title: Friday the 13th (2009 film)

text: Though the producers decided that "Friday the 13th" would not be an origin story, they said that they wanted to work out a logical origin story for Jason that would provide a sense of history as the film progressed. Form and Fuller explained that the audience gets to see how Jason attains his famous hockey mask, and is given a reason for why he puts it on. Jason would transition from wearing a bag over his head—similar to the one seen in "Friday the 13th Part 2"—to finding and wearing his hockey mask, whereas in "Friday the 13th Part III" he obtains the mask off-screen and comes out of a barn already wearing it.