The hydrogen line, 21-centimeter line or H I line refers to the electromagnetic radiation spectral line, created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation is at the precise frequency of 1420405751.7667±0.0009 Hz, equivalent to the vacuum wavelength of 21.1061140542 cm in free space. This wavelength falls within the microwave region of the electromagnetic spectrum, it is observed in radio astronomy, since those radio waves can penetrate the large clouds of interstellar cosmic dust that are opaque to visible light; this line is the theoretical basis of Hydrogen maser. The microwaves of the hydrogen line come from the atomic transition of an electron between the two hyperfine levels of the hydrogen 1 s ground state that have an energy difference of ≈ 5.87433 μeV. It is called the spin-flip transition; the frequency, ν, of the quanta that are emitted by this transition between two different energy levels is given by the Planck–Einstein relation E = hν.

According to that relation, the photon energy of a 1,420,405,751.7667 Hz photon is ≈ 5.87433 μeV. The constant of proportionality, h, is known as the Planck constant; the ground state of neutral hydrogen consists of an electron bound to a proton. Both the electron and the proton have intrinsic magnetic dipole moments ascribed to their spin, whose interaction results in a slight increase in energy when the spins are parallel, a decrease when antiparallel; the fact that only parallel and antiparallel states are allowed is a result of the quantum mechanical discretization of the total angular momentum of the system. When the spins are parallel, the magnetic dipole moments are antiparallel, thus one would expect this configuration to have lower energy just as two magnets will align so that the north pole of one is closest to the south pole of the other; this logic fails here because the wave functions of the proton overlap. The magnetic dipole moments are therefore best thought of as tiny current loops.

As parallel currents attract, the parallel magnetic dipole moments have lower energy. The transition has an energy difference of 5.87433 μeV that when applied in the Planck equation gives: λ = 1 ν ⋅ c = h E ⋅ c = 4.1357 ⋅ 10 − 15 eV s 5.874 33 ⋅ 10 − 6 eV ⋅ 2.9979 ⋅ 10 8 m s − 1 = 0.211 06 m = 21.106 cm where h is the Planck constant and c is the speed of light. This transition is forbidden with an small transition rate of 2.9×10−15 s−1, a mean lifetime of the excited state of around 10 million years. A spontaneous occurrence of the transition is unlikely to be seen in a laboratory on Earth, but it can be artificially induced using a hydrogen maser, it is observed in astronomical settings such as hydrogen clouds in our galaxy and others. Owing to its long lifetime, the line has an small natural width, so most broadening is due to Doppler shifts caused by bulk motion or nonzero temperature of the emitting regions. During the 1930s, it was noticed that there was a radio'hiss' that varied on a daily cycle and appeared to be extraterrestrial in origin.

After initial suggestions that this was due to the Sun, it was observed that the radio waves seemed to propagate from the centre of the Galaxy. These discoveries were published in 1940 and were noted by Jan Oort who knew that significant advances could be made in astronomy if there were emission lines in the radio part of the spectrum, he referred this to Hendrik van de Hulst who, in 1944, predicted that neutral hydrogen could produce radiation at a frequency of 1420.4058 MHz due to two spaced energy levels in the ground state of the hydrogen atom. The 21 cm line was first detected in 1951 by Ewen and Purcell at Harvard University, published after their data was corroborated by Dutch astronomers Muller and Oort, by Christiansen and Hindman in Australia. After 1952 the first maps of the neutral hydrogen in the Galaxy were made, revealed for the first time the spiral structure of the Milky Way; the 21 cm spectral line appears within the radio spectrum. Electromagnetic energy in this range can pass through the Earth's atmosphere and be observed from the Earth with little interference.

Assuming that the hydrogen atoms are uniformly distributed throughout the galaxy, each line of sight through the galaxy will reveal a hydrogen line. The only difference between each of these lines is the doppler shift. Hence, one can calculate the relative speed of each arm of our galaxy; the rotation curve of our galaxy has been calculated using the 21 cm hydrogen line. It is possible to use the plot of the rotation curve and the velocity to determine the distance to a certain point within the galaxy. Hydrogen line observations have been used indirectly to calculate the mass of galaxies, to put limits on any changes over time o

Bob Pattillo is an entrepreneur and founder of Gray Ghost Ventures, Gray Matters Capital, First Light Ventures, GMC Ratings, GGMF, ISFC, IDEX and co-founder of Bellwether Fund, ASA Intl, Village Capital. Gray Matters Capital is an Impact Investing Enterprise that invests in education for low income students in emerging markets. GMC's mission is an education leading to a purpose filled life for 100 million women, he has served as an adviser to many global investors and foundations, including Omidyar, Goldman Sachs, TONIIC, JP Morgan. His funds and/or investments have participated in sales of RentBureau / Experian, Movirtu / BlackBerry Limited, Cell Bazaar / Telenor, his interviews are featured by SOCAP and Emory University In real estate, he took over a family business founded Robert Pattillo Properties in 1994 and pioneered the "STCDE" shell, a spec building concept that took Robert Pattillo Properties to 8th on the list of the largest industrial developers in the United States. He began working in microfinance in 1998 and sold a 54-year-old business in 2003 from the influence of his 11-year-old daughter to focus on impact investment and enterprise development.

In 2001, Pattillo founded the Gray Ghost Microfinance Fund, a $69m fund that focuses on regional equity microfinance funds that supply start-up and expansion capital to microfinance institutions around the world. In 2016 according to a report by BCorp four of the top five impact funds over the last 14 years were led by investments from GGMF. In 2006, Pattillo began investing in social enterprise through his Gray Matters Capital Foundation, in 2008 he invested in Gray Ghost DOEN Social Ventures Coöperatief, alongside the DOEN Foundation; the portfolio includes d.light, MKopa, BKash. In its work in social ventures, he has coinvested alongside Acumen Fund, the Omidyar Network, Shell Foundation. Pattillo helped found Village Capital and IDEX. Pattillo has been named one of Forbes' Top 30 social entrepreneurs of 2011, he has served as a Director of Accion International, Microvest, ASA International, Mix Markets, d.light, Council for Microfinance Equity Funds, the Indian School Finance Company. He was the Keynote Speaker at SOCAP, The UN Conference on Microfinance, Goldman Sachs Global Partners meeting, Accion Global Conference, Consortium Launch.

Gray Matters Capital First Light India Accelerator Village Capital Global Impact Investing Network Bob Pattillo Creativity Conversation, Emory University Bob Pattillo SOCAP Interview Stanford Social Innovation Review, Private Schools for the Poor Harvard Business Review, Creating Shared Value

Olmsted Subdivision Historic District is a historic district bounded by New Ocean St/Paradise Road, Swampscott Avenue, Redington Street and Burrill Street in Swampscott, Massachusetts. According to the May 2005 Massachusetts Heritage Landscape Inventory Program, “This large residential neighborhood was planned by Frederick Law Olmsted, Sr. in 1888 at the request of the Swampscott Land Trust. The 130-acre estate had belonged to E. Redington Mudge. Olmsted’s plan with its curvilinear roads layout, traffic islands, entrance parkway, use of the topographic features and fine architecture is remarkably well preserved; the roads and traffic islands are maintained by the town. The shapes have not been altered. Part of the original plan showed “Overlook Park” with steps leading to it at the end of Monument Avenue, it was never constructed and in its place is a huge house on top of the hill. The original subdivision had 191 lots of varying sizes and shapes.” It was added to the National Register of Historic Places in 2002.

At the same time, many argue that Olmsted never set foot in Swampscott, the original plan was only for a strip of land that begins at Humphrey Street and concludes where Monument Road turns into Walker Road. National Register of Historic Places listings in Essex County, Massachusetts

Joe Walsh is an American musician. Known as a member of the rock band Eagles, Walsh is a solo recording artist, his highest charting song is "A Life of Illusion", which reached number-one on Hot Mainstream Rock Tracks. Note: Other songs in the Eagles catalog that were sung and written by Walsh include "Life's Been Good" and "All Night Long", from Walsh's solo career, which were included on Eagles Live, "Funk #49", from Walsh's days in the James Gang, was included on the fourth "Millennium Concert" disc of the Eagles box set Selected Works: 1972-1999; the band has been known to play "Rocky Mountain Way," as seen on the Farewell Tour I DVD. These are not Eagles songs however, since the studio cuts did not originate under the Eagles name

Keuruu is a town and municipality of Finland. It is part of the Central Finland region; the municipality has a population of 9,757 and covers an area of 1,430.57 square kilometres of which 172.4 km2 is water. The population density is 7.75 inhabitants per square kilometre. The town center and Haapamäki village are both the most populated places in Keuruu. Neighbouring municipalities are Multia, Mänttä-Vilppula, Petäjävesi, Virrat and Ähtäri; the municipality is unilingually Finnish. The municipality of Pihlajavesi was consolidated with Keuruu in 1969. There are 316 lakes in Keuruu, the largest of which are Keurusselkä-Ukonselkä, Pihlajavesi and Liesjärvi. Einari Vuorela, writer Hannele Huovi, writer Joni Lius, ice hockey player Jukka Rautakorpi, professional ice hockey coach Kalevi Sorsa, former Prime Minister of Finland Matti Kassila, film director Mirjami Kuosmanen, actress Olli Palola, ice hockey player Pirkko Vahtero, graphic designer and heraldist Matias Saxberg and murderer Keuruu is twinned with: Jõgeva, Estonia Szarvas, Hungary Notes Media related to Keuruu at Wikimedia Commons Town of Keuruu – Official website Keuruun Pallo – A football club, infamous for losing their every single game in the Finnish division 2

Pokémon Adventures, known in Japan as Pocket Monsters Special, is a Japanese manga series published by Shogakukan. The story arcs of the series are based on most of the Pokémon video games released by Nintendo and, as such, the main characters of the series have the name of their video game. Since the manga is based on the video games, there are some delays with the serialization since the authors need to have seen the games in order to continue with the plot; the series is written by Hidenori Kusaka, it is illustrated by Mato during the first nine volumes, while Satoshi Yamamoto starts illustrating it since the tenth volume. The Japanese publisher Shogakukan has been releasing the individual chapters in tankōbon format with the first one being released on August 8, 1997 and 52 tankōbon have been released; the distributing company Viz Media has licensed the series for English in the United States. Viz released the first seven volumes of the series in tankōbon format from July 6, 2000 to January 2003 as well as in magazine format.

During 2006 they released two volumes with the name of The Best of Pokémon Adventures which are various chapters from the first two arcs put into one book. On June 1, 2009, Viz restarted publishing the tankōbon volumes, are now up to volume 9 as of October 2010. Volume 10 is scheduled for December 2010, volumes 11, 12 and volume 30 of the DP arc are all scheduled for 2011 as well. However, these releases feature both visual and dialogue edits not found in the original English release and original Japanese tankobon release. HeartGold & SoulSilver chapter Black & White chapter Black 2 & White 2 chapter 2 rounds in Black 2 & White 2 Chapter, 39 rounds & 7 side stories in X & Y Chapter, 22 rounds in Omega Ruby & Alpha Sapphire Chapter and 26 rounds in Sun, Ultra Sun & Ultra Moon Chapter are yet to be published in a tankōbon volume, but have been printed in the magazine, mini volumes, or published online; these titles, their order, are subject to change, both in collection into tankōbon, translation into English.

Black 2 & White 2 Chapter X & Y Chapter Omega Ruby & Alpha Sapphire Chapter Sun, Ultra Sun & Ultra Moon chapter Official Pokémon Adventures website of Viz Media Official Pokémon Adventures website