A molecular machine, nanite, or nanomachine, refers to any discrete number of molecular components that produce quasi-mechanical movements in response to specific stimuli. In biology, macromolecular machines perform tasks essential for life such as DNA replication and ATP synthesis; the expression is more applied to molecules that mimic functions that occur at the macroscopic level. The term is common in nanotechnology where a number of complex molecular machines have been proposed that are aimed at the goal of constructing a molecular assembler. For the last several decades and physicists alike have attempted, with varying degrees of success, to miniaturize machines found in the macroscopic world. Molecular machines research is at the forefront with the 2016 Nobel Prize in Chemistry being awarded to Jean-Pierre Sauvage, Sir J. Fraser Stoddart and Bernard L. Feringa for the design and synthesis of molecular machines. Molecular machines can be divided into two broad categories. In general, artificial molecular machines refer to molecules that are artificially designed and synthesized whereas biological molecular machines can be found in nature.
A wide variety of artificial molecular machines have been synthesized by chemists which are rather simple and small compared to biological molecular machines. The first AMM, a molecular shuttle, was synthesized by Sir J. Fraser Stoddart. A molecular shuttle is a rotaxane molecule where a ring is mechanically interlocked onto an axle with two bulky stoppers; the ring can move between two binding sites with various stimuli such as light, pH, ions. As the authors of this 1991 JACS paper noted: “Insofar as it becomes possible to control the movement of one molecular component with respect to the other in a rotaxane, the technology for building molecular machines will emerge.”, mechanically interlocked molecular architectures spearheaded AMM design and synthesis as they provide directed molecular motion. Today a wide variety of AMMs exists as listed below. Molecular motors are molecules that are capable of rotary motion around a double bond. Single bond rotary motors are fueled by chemical reactions whereas double bond rotary motors are fueled by light.
The rotation speed of the motor can be tuned by careful molecular design. Carbon nanotube nanomotors have been produced. A molecular propeller is a molecule that can propel fluids when rotated, due to its special shape, designed in analogy to macroscopic propellers, it has several molecular-scale blades attached at a certain pitch angle around the circumference of a nanoscale shaft. See molecular gyroscope. A molecular switch is a molecule; the molecules may be shifted between the states in response to changes in pH, temperature, an electric current, microenvironment, or the presence of a ligand. A molecular shuttle is a molecule capable of shuttling molecules or ions from one location to another. A common molecular shuttle consists of a rotaxane where the macrocycle can move between two sites or stations along the dumbbell backbone. Nanocars are single molecule vehicles that resemble macroscopic automobiles and are important for understanding how to control molecular diffusion on surfaces; the first nanocars were synthesized by James M. Tour in 2005.
They had 4 molecular wheels attached to the four corners. In 2011, Ben Feringa and co-workers synthesized the first motorized nanocar which had molecular motors attached to the chassis as rotating wheels; the authors were able to demonstrate directional motion of the nanocar on a copper surface by providing energy from a scanning tunneling microscope tip. In 2017, worlds first Nanocar race took place in France. A molecular balance is a molecule that can interconvert between two and more conformational or configurational states in response to the dynamic of multiple intra- and intermolecular driving forces, such as hydrogen bonding, solvophobic/hydrophobic effects, π interactions, steric and dispersion interactions. Molecular tweezers are host molecules capable of holding items between their two arms; the open cavity of the molecular tweezers binds items using non-covalent bonding including hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, π interactions, or electrostatic effects.
Examples of molecular tweezers have been reported that are constructed from DNA and are considered DNA machines. A molecular sensor is a molecule. Molecular sensors combine molecular recognition with some form of reporter, so the presence of the item can be observed. A molecular logic gate is a molecule that performs a logical operation on one or more logic inputs and produces a single logic output. Unlike a molecular sensor, the molecular logic gate will only output when a particular combination of inputs are present. A molecular assembler is a molecular machine able to guide chemical reactions by positioning reactive molecules with precision. A molecular hinge is a molecule that can be selectively switched from one configuration to another in a reversible fashion; such configurations must have distinguishable geometries, for instance, Cis or Trans isomers of a V-shape molecule. Azo compounds perform Cis–trans isomerism upon receiving UV-Vis light; the most complex macromolecular machines are found within cells in the form of multi-protein complexes.
Some biological machines are motor proteins, such as myosin, responsible for muscle contraction, which moves cargo inside cells away from the nucleus along microtubules, and
My-HiME is an anime series, created by Sunrise. Directed by Masakazu Obara and written by Hiroyuki Yoshino, the series premiered in Japan on TV Tokyo from September 2004 to March 2005; the show focuses on the lives of HiMEs—girls with the capacity to materialize photons—gathered at Fuka Academy for a secret purpose. The series was licensed for North American distribution by Bandai Entertainment and European distribution by Bandai's European subsidiary, with the first American DVD released at the end of March 2006. Bandai released the Complete Collection DVD set in America on October 7, 2008, it is shown on iaTV in the mid-2000s and on Comcast’s Anime Selects on Demand but only for a limited time. At Otakon 2013, Funimation Entertainment had announced that they have rescued My-HiME, along with a handful of other former BEI titles, they announced at the 2017 New York Comic Con that they will release My-HiMe, My-Otome, a My-Otome Zwei + My-Otome 0: S.ifr pack, all on Blu-Ray + DVD combo packs on January 8, 2018.
The story centers on Mai Tokiha, a ordinary high-school girl who has transferred to the prestigious Fuuka Academy with her sickly younger brother, Takumi Tokiha. The elite Fuuka Academy harbors a number of mysteries. Soon after arriving at the Academy, Mai finds herself bound to a Child, a part-spiritual, part-mechanical creature, that can only be summoned and controlled by girls with the HiME mark. Mai is told that there are twelve other girls who are marked, that they must use their powers to protect the unwitting human populace from Orphans, monstrous creatures with abilities similar to the HiME's Children. Mai is reluctant to become involved at first, because of her protective role towards her brother. However, the other HiME begin to manifest around her, each with different motivations and goals for using her powers; as the Orphans become more numerous and more aggressive Mai and her friends are drawn into the conflict, but Mai and the other HiME soon find out the Orphans are not the only kind of enemy they have to fight, as the cause of all of this is revealed, they find themselves facing the dark secret about their destiny.
The show's cast of characters is composed of students and staff at Fuuka Academy, with the emphasis on the female cast. Although most of the cast is introduced by the second episode, only a few characters are disclosed as HiMEs; the main characters are the hardworking, caring Mai Tokiha, the catlike Mikoto Minagi, the cold beauty Natsuki Kuga. Other characters are shown with a wide range of relationships. Director Masakazu Obara states that he "wanted to reverse the roles that men and women play," placing females in the lead roles. Mai is the protagonist of the Mai-Hime anime series, she is portrayed as a self-reliant person, hesitant to tell others about her problems. She is a first-year high school student, her roommate is Mikoto Minagi, her stated hobbies are taking care of Takumi. Mikoto is a third-grade middle school student, she loves to be with Mai at her side or clinging to her. She has a problem with spicy food, consuming it sends her into rampages while looking for water. Natsuki is portrayed as a serious, rational blue-haired female.
Natsuki doesn't want to work with Mikoto or Mai, but as the series progresses the three fight off the various Orphans at the academy, become friends. A My-Hime manga series was developed by Sunrise, it was first serialized in Akita Shoten's Shōnen Champion and published in North America by TOKYOPOP. It follows an alternate storyline at Fuka Academy where Mai and Natsuki become roommates. An anime spin-off, entitled My-Otome, premiered in Japan from October 2005 to March 2006; this series contains many characters with the same name and similar appearance as the characters of My-HiME, but it is set in a far future timeline. A PlayStation 2 video game, Mai-HiME: Unmei no Keitōju was developed by Marvelous Interactive and released in Japan on June 30, 2005; this adventure game follows a storyline different from the manga series. A remake, Mai-Hime - Unmei no Keitouju Shura, was released for the PC. Two PlayStation Portable fighting games, Mai-HiME Bakuretsu! Fuuka Gakuen Gekitoushi?! and Mai-HiME Senretsu!
Shin Fuuka Gakuen Gekitoushi!!, both developed by Sunrise Interactive, were released. A parody trailer for a Mai-Hime movie was included in the first DVD of Mai-Otome, with the title Fuuka Wars or The Great Battle of Fuuka with a release date of 20006. A second manga series titled, it was first serialized in Dengeki Daioh in 2010. Official My-Hime website TV Tokyo's My-Hime website My-HiME at Anime News Network's encyclopedia
Tokuma Shoten Publishing Co. Ltd. is a publisher in Japan, headquartered in Shinagawa, Tokyo. The company was established in 1954 by Yasuyoshi Tokuma in Tokyo; the company’s product portfolio includes music publishing, video game publishing, anime, magazines and books. Companies that were part of Tokuma Shoten include Studio Ghibli, Daiei Film and the record label Tokuma Japan Communications. After the founder of the company, Yasuyoshi Tokuma died on September 20, 2000, an asset management occurred. Tokuma Shoten executed a corporate spin-off with Studio Ghibli, turning the company’s anime division as a separate company again in 2005. Tokuma Shoten sold off Tokuma Japan Communications to Daiichi Kosho in October 2001, Daiei Films was purchased by Kadokawa Corporation in November 2002. Since 2005, the company has streamlined itself to focus on the publication of print media and the airing of its adapted properties to TV and feature film. On 17 March 2017, the company was acquired by Culture Convenience Club.
The deal was completed at the end of March. On March 1954, Tokuma was established as East-West Entertainment Publishing in Shimbashi 3-chome, Minato-ku, Tokyo with a capital of 1,000,000 yen; the company took over the publishing rights for Weekly Asahi Performing Arts, a publication which dated back from January 1951. The Osaka branch office opened in the same year. On September 1958, the company’s name was changed to Asahi Performing Arts Publishing. On April 1961, Asahi Performing Arts Publishing spun off their book publishing business as Tokuma Shoten. On October 1967, Asahi Performing Arts Publishing and Tokuma Publishing merged and became known as Tokuma Shoten Company. In the same month, the monthly issue of Problem novel was launched. On July 1978, the monthly publication Animage was launched, on October 1980, the Tokuma Bunko brand was launched. On March 1984, the company co-produced with Hakuhodo Inc. on a project commemorating the company’s 30th Anniversary. The company funded films by Studio Ghibli, starting with Nausicaa of the Valley of the Wind.
On February 1988, the company released the anime series Legend of the Galactic Heroes by Yoshiki Tanaka. On April of the same year, My Neighbour Totoro was released, on September 1988, the monthly publication GoodsPress was launched. On 1989, Tokuma Shoten hired Streamline Pictures to produce the English language version of the 1986 film Laputa: Castle in the Sky directed by Hayao Miyazaki, its 1992 English dubbing of The Castle of Cagliostro. In 1988, Streamline dubbed My Neighbor Totoro and Kiki's Delivery Service, both dubbed under the supervision of Gregory Snegoff for Tokuma Shoten, although this collaboration was only used as in-flight films by Japan Airlines who, at the time, licensed them from Tokuma Shoten; the airline showed the movies during their flights between the United States. On May 1994, the company launched a children’s picture and literature book as a 40th anniversary commemoration project. On August 1996, Disney and Tokuma Shoten formed a partnership in which Buena Vista Pictures would be the sole international distributor for Tokuma Shoten's Studio Ghibli animated films.
Since all three afore-mentioned films by Miyazaki at Studio Ghibli that were dubbed by Streamline have been re-dubbed by Disney. On June 1, 1997, Tokuma Shoten Publishing consolidated its media operations by merging Studio Ghibli, Tokuma Shoten Intermedia software and Tokuma International under one location. On February 1999, the 30th anniversary commemorative prize issue novel, was held at the 19th Japan SF award, with a presentation award ceremony of a short novel labelled as Tokuma literary award. On July 2001, Spirited Away was released, it would go on to break numerous records and became the most successful film during that era in Japanese history, grossing over $289,000,000 worldwide. On November 2004, Howl's Moving Castle was released. Along with the movie, the original book of the same name was a success. Between 1999 and 2005, Studio Ghibli was a subsidiary brand of Tokuma Shoten, that partnership ended on April 2005, when Studio Ghibli was spun off from Tokuma Shoten and was re-established as an independent company with a relocated headquarters.
On September 2006, the monthly publication Comic Ryu was launched. On October 2006, Weekly Asahi Performing Arts celebrated its 50th anniversary. On May 2007, the animated TV series Dennou coli was in production, on May 2011, Rongu Blessing’s Long Blessed Diet produced a cumulative total of 1.16 million views. On January 2012, the monthly publication Volt was launched, on September 2012, Sweet Girly Artbook Larme launched. On April 2013, the TV drama Tokimeki Deka Tachibana, based on Tokuma Comics Sakado by Sadako original, Torii Tori Drawing was broadcast on TV Tokyo as a series. On June 2013, Tokuma Bunko’s drama Traffic by Shibata Yoshiki is broadcast on NHK. On May 2014, the company released the movie Wood Job! ~ Original God of Dreams nationwide. God's Honorable Emotional Daily by Miura Shin was released. On July 2015, the Comic Ryo TV animated series Monster Musume. On January 2017, Tokuma Bunko launched the drama Today is a good day by Maha Harada, broadcast at WOWOW. On March 2017, Tokuma Shoten became a subsidiary of Culture Convenience Club through an acquisition exchange of shares.
On April 2017, Comic Ruy’s original TV animated series and Kura Six by Tetsuya Imai was broadcast. On July 2017, Tokuma Bunko’s drama Akira and Akira by Ike Well Jun was broadcast at WOWOW. Comic Ryu’s original TV animated series Centaur’s Trouble by Kei Murayama was broadcast. Animage BestGear Chara Chara Selection Famimaga (ファミリーコンピュータマガジン, Family Computer M
My-Otome Zwei is a Japanese OVA anime series, created by Sunrise. Directed by Masakazu Obara and written by Hiroyuki Yoshino, it consists of four episodes, which were released across three-month intervals and is the sequel to the original My-Otome anime series, it is published in Japan by Bandai Visual and North America by Bandai Entertainment. At Otakon 2013, Funimation Entertainment had announced that they have rescued My-Otome Zwei, along with a handful of other former BEI titles, they announced at the 2017 New York Comic Con that they will release My-HiMe, My-Otome, a My-Otome Zwei + My-Otome 0: S.ifr pack, all on Blu-Ray + DVD combo packs on January 8, 2018. They will start pre-orders on October 15, 2017. Similar to its predecessors My-HiME and My-Otome, the title is a pun, which derives from the visual similarity of the Latin letter "Z" to the kanji "乙", the first of the two characters in the word 乙女 otome "maiden". On the logo, the two similar glyphs are shown superimposed on one another.
My-Otome Zwei takes place one year after the events of My-Otome. Arika is now a full-fledged Otome and Nagi is incarcerated in a prison somewhere in Aries; the various nations are at peace with one another and plan to hold S. O. L. T. to discuss limiting the numbers of Otome. A mission to destroy a meteor threatening to collide with Earl sets into motion a chain of events which result in a mysterious shadowy figure attacking Garderobe and several Otome as well as a new, more powerful version of Slave appearing across the planet. To make matters worse, Queen Mashiro disappears following an argument with Arika; the series follows Arika's search for Mashiro as well as Garderobe's attempts to uncover the truth behind the shadowy figure. Each release is available in two versions; each Volume's Special Package contains: A DVD containing the 30-minute episode A 3-track music CD containing the episode's ending song, its off vocal version and an audio commentary A figurine A picture labelThe Volume 1 Special Package included an illustration book.
The first volume was released November 24, 2006, the second volume was released February 23, 2007, the third volume was released May 25, 2007, the fourth and final volume was released August 24, 2007. Ending themes Believe ~Eien no Kizuna~ by Mika Kikuchi Storm by Ami Koshimizu Egao no Iro wa Niji no Iro by Yukana Otome wa DO MY BEST desho? 2007Ver. by Mika Kikuchi, Ami Koshimizu, Mai Nakahara, Saeko Chiba and Ai Shimizu The My-Otome Zwei manga is being serialised in Champion RED, done by Abeno Chako. Having nothing to do with the original My-Otome manga, it follows the storyline of the OVA at first but diverges. My-HiME My-Otome My-Otome 0: S.ifr Official website My-Otome Zwei at Anime News Network's encyclopedia
The PlayStation 2 is a home video game console, developed by Sony Computer Entertainment. It is the successor to the original PlayStation console and is the second iteration in the PlayStation lineup of consoles, it was released in 2000 and competed with Sega's Dreamcast, Nintendo's GameCube and Microsoft's Xbox in the sixth generation of video game consoles. Announced in 1999, the PlayStation 2 offered backwards compatibility for its predecessor's DualShock controller, as well as for its games; the PlayStation 2 is the best-selling video game console of all time, selling over 155 million units, with 150 million confirmed by Sony in 2011. More than 3,874 game titles have been released for the PS2 since launch, more than 1.5 billion copies have been sold. Sony manufactured several smaller, lighter revisions of the console known as Slimline models in 2004. In 2006, Sony announced and launched its successor, the PlayStation 3. With the release of its successor, the PlayStation 2 remained popular well into the seventh generation and continued to be produced until January 4, 2013, when Sony announced that the PlayStation 2 had been discontinued after 12 years of production – one of the longest runs for a video game console.
Despite the announcement, new games for the console continued to be produced until the end of 2013, including Final Fantasy XI: Seekers of Adoulin for Japan, FIFA 13 for North America, Pro Evolution Soccer 2014 for Europe. Repair services for the system in Japan ended on September 7, 2018. Though Sony has kept details of the PlayStation 2's development secret, work on the console began around the time that the original PlayStation was released. Insiders stated that it was developed in the U. S. West Coast by former members of Argonaut Software. By 1997 word had leaked to the press that the console would have backwards compatibility with the original PlayStation, a built-in DVD player, Internet connectivity. Sony announced the PlayStation 2 on March 1, 1999; the video game console was positioned as a competitor to Sega's Dreamcast, the first sixth-generation console to be released, although the main rivals of the PS2 were Nintendo's GameCube and Microsoft's Xbox. The Dreamcast itself launched successfully in North America that year, selling over 500,000 units within two weeks.
Soon after the Dreamcast's North American launch, Sony unveiled the PlayStation 2 at the Tokyo Game Show on September 20, 1999. Sony showed playable demos of upcoming PlayStation 2 games including Gran Turismo 2000 and Tekken Tag Tournament – which showed the console's graphic abilities and power; the PS2 was launched in March 2000 in Japan, October in North America, November in Europe. Sales of the console and accessories pulled in $250 million on the first day, beating the $97 million made on the first day of the Dreamcast. Directly after its release, it was difficult to find PS2 units on retailer shelves due to manufacturing delays. Another option was purchasing the console online through auction websites such as eBay, where people paid over a thousand dollars for the console; the PS2 sold well on the basis of the strength of the PlayStation brand and the console's backward compatibility, selling over 980,000 units in Japan by March 5, 2000, one day after launch. This allowed the PS2 to tap the large install base established by the PlayStation – another major selling point over the competition.
Sony added new development kits for game developers and more PS2 units for consumers. The PS2's built-in functionality expanded its audience beyond the gamer, as its debut pricing was the same or less than a standalone DVD player; this made the console a low cost entry into the home theater market. The success of the PS2 at the end of 2000 caused Sega problems both financially and competitively, Sega announced the discontinuation of the Dreamcast in March 2001, just 18 months after its successful launch; the PS2 remained as the only active sixth generation console for over 6 months, before it would face competition from newer rivals. Many analysts predicted a close three-way matchup among the three consoles. While the PlayStation 2 theoretically had the weakest specification of the three, it had a head start due to its installed base plus strong developer commitment, as well as a built-in DVD player. While the PlayStation 2's initial games lineup was considered mediocre, this changed during the 2001 holiday season with the release of several blockbuster games that maintained the PS2's sales momentum and held off its newer rivals.
Sony countered the Xbox by temporarily securing PlayStation 2 exclusives for anticipated games such as the Grand Theft Auto series and Metal Gear Solid 2: Sons of Liberty. Sony cut the price of the console in May 2002 from US$299 to $199 in North America, making it the same price as the GameCube and $100 less than the Xbox, it planned to cut the price in Japan around that time. It cut the price twice in Japan in 2003. In 2006, Sony cut the cost of the console in anticipation of the release of the PlayStation 3. Sony, unlike Sega with its Dreamcast placed little emphasis on online gaming during its first few years, although that changed upon the launch of the online-capable Xbox. Coinciding with the release of Xbox Live, Sony released the PlayStation Network Adapter in late 2002, with several online first–party titles released alongside it, such as SOCOM: U. S. Navy SEALs to demon
Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times. Earth's axis of rotation is tilted with respect to its orbital plane; the gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, slows its rotation. Earth is the largest of the four terrestrial planets. Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water by oceans; the remaining 29% is land consisting of continents and islands that together have many lakes and other sources of water that contribute to the hydrosphere.
The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, a convecting mantle that drives plate tectonics. Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms; some geological evidence indicates. Since the combination of Earth's distance from the Sun, physical properties, geological history have allowed life to evolve and thrive. In the history of the Earth, biodiversity has gone through long periods of expansion punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely. Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.
Humans have developed diverse cultures. The modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most spelled eorðe, it has cognates in every Germanic language, their proto-Germanic root has been reconstructed as *erþō. In its earliest appearances, eorðe was being used to translate the many senses of Latin terra and Greek γῆ: the ground, its soil, dry land, the human world, the surface of the world, the globe itself; as with Terra and Gaia, Earth was a personified goddess in Germanic paganism: the Angles were listed by Tacitus as among the devotees of Nerthus, Norse mythology included Jörð, a giantess given as the mother of Thor. Earth was written in lowercase, from early Middle English, its definite sense as "the globe" was expressed as the earth. By Early Modern English, many nouns were capitalized, the earth became the Earth when referenced along with other heavenly bodies. More the name is sometimes given as Earth, by analogy with the names of the other planets.
House styles now vary: Oxford spelling recognizes the lowercase form as the most common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name but writes it in lowercase when preceded by the, it always appears in lowercase in colloquial expressions such as "what on earth are you doing?" The oldest material found in the Solar System is dated to 4.5672±0.0006 billion years ago. By 4.54±0.04 Bya the primordial Earth had formed. The bodies in the Solar System evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, dust. According to nebular theory, planetesimals formed by accretion, with the primordial Earth taking 10–20 million years to form. A subject of research is the formation of some 4.53 Bya. A leading hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, hit Earth.
In this view, the mass of Theia was 10 percent of Earth, it hit Earth with a glancing blow and some of its mass merged with Earth. Between 4.1 and 3.8 Bya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon and, by inference, to that of Earth. Earth's atmosphere and oceans were formed by volcanic outgassing. Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids and comets. In this model, atmospheric "greenhouse gases" kept the oceans from freezing when the newly forming Sun had only 70% of its current luminosity. By 3.5 Bya, Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind. A crust formed; the two models that explain land mass propose either a steady growth to the present-day forms or, more a rapid growth early in Earth history followed by a long-term steady continental area. Continents formed by plate tectonics