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Natural nuclear fission reactor

A fossil natural nuclear fission reactor is a uranium deposit where self-sustaining nuclear chain reactions have occurred. This can be examined by analysis of isotope ratios; the conditions under which a natural nuclear reactor could exist had been predicted in 1956 by Paul Kazuo Kuroda. The phenomenon was discovered in 1972 in Oklo, Gabon by French physicist Francis Perrin under conditions similar to what was predicted. Oklo is the only known location for this in the world and consists of 16 sites at which self-sustaining nuclear fission reactions are thought to have taken place 1.7 billion years ago, ran for a few hundred thousand years, averaging less than 100 kW of thermal power during that time. In May 1972 at the Pierrelatte uranium enrichment facility in France, routine mass spectrometry comparing UF6 samples from the Oklo Mine, located in Gabon, showed a discrepancy in the amount of the 235U isotope; the concentration is 0.72% while these samples had only 0.60%, a significant difference.

This discrepancy required explanation, as all civilian uranium handling facilities must meticulously account for all fissionable isotopes to ensure that none are diverted for weapons purposes. Thus the French Commissariat à l'énergie atomique began an investigation. A series of measurements of the relative abundances of the two most significant isotopes of the uranium mined at Oklo showed anomalous results compared to those obtained for uranium from other mines. Further investigations into this uranium deposit discovered uranium ore with a 235U concentration as low as 0.44%. Subsequent examination of isotopes of fission products such as neodymium and ruthenium showed anomalies, as described in more detail below; this loss in 235U is what happens in a nuclear reactor. A possible explanation, was that the uranium ore had operated as a natural fission reactor. Other observations led to the same conclusion, on September 25, 1972, the CEA announced their finding that self-sustaining nuclear chain reactions had occurred on Earth about 2 billion years ago.

Other natural nuclear fission reactors were discovered in the region. Neodymium and other elements were found with isotopic compositions different from what is found on Earth. For example, Oklo contained less than 6% of the 142Nd isotope while natural neodymium contains 27%. Subtracting the natural isotopic Nd abundance from the Oklo-Nd, the isotopic composition matched that produced by the fission of 235U. Similar investigations into the isotopic ratios of ruthenium at Oklo found a much higher 99Ru concentration than otherwise occurring; this anomaly could be explained by the decay of 99Tc to 99Ru. In the bar chart the normal natural isotope signature of ruthenium is compared with that for fission product ruthenium, the result of the fission of 235U with thermal neutrons, it is clear. The level of 100Ru in the fission product mixture is low because of a long-lived isotope of molybdenum. On the time scale of when the reactors were in operation little decay to 100Ru will have occurred; the natural nuclear reactor formed when a uranium-rich mineral deposit became inundated with groundwater that acted as a neutron moderator, a nuclear chain reaction took place.

The heat generated from the nuclear fission caused the groundwater to boil away, which slowed or stopped the reaction. After cooling of the mineral deposit, the water returned, the reaction restarted, completing a full cycle every 3 hours; the fission reaction cycles continued for hundreds of thousands of years and ended when the ever-decreasing fissile materials no longer could sustain a chain reaction. Fission of uranium produces five known isotopes of the fission-product gas xenon; the concentrations of xenon isotopes, found trapped in mineral formations 2 billion years make it possible to calculate the specific time intervals of reactor operation: 30 minutes of criticality followed by 2 hours and 30 minutes of cooling down to complete a 3-hour cycle. A key factor that made the reaction possible was that, at the time the reactor went critical 1.7 billion years ago, the fissile isotope 235U made up about 3.1% of the natural uranium, comparable to the amount used in some of today's reactors.

Because 235U has a shorter half-life than 238U, thus decays more the current abundance of 235U in natural uranium is about 0.70–0.72%. A natural nuclear reactor is therefore no longer possible on Earth without heavy graphite; the Oklo uranium ore deposits are the only known sites. Other rich uranium ore bodies would have had sufficient uranium to support nuclear reactions at that time, but the combination of uranium and physical conditions needed to support the chain reaction was unique, as far as is known, to the Oklo ore bodies. Another factor which contributed to the start of the Oklo natural nuclear reactor at 2 billion years, rather than earlier, was the increasing oxygen content in the Earth's atmosphere. Uranium is present in the rocks of the earth, the abundance of fissile 235U was at least 3% or higher at all times prior to reactor startup. Uranium is soluble in water only in the presence of oxygen. Therefore, the rising oxygen levels during the aging of the Earth may have allowed uranium to be dissolved and transported with groundwater to places where a high enough concentration could accumulate to form rich uranium ore bodies.

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Countess Palatine Barbara of Zweibrücken-Neuburg

Countess Palatine Barbara of Zweibrücken-Neuburg was a Countess Palatine of Zweibrücken by birth and by marriage Countess of Oettingen-Oettingen. Barbara was born in Neuburg, a daughter of Duke and Count Palatine Wolfgang of Zweibrücken from his marriage to Anna, the daughter of Philip I, Landgrave of Hesse. On 7 November 1591, she married Count Gottfried of Oettingen-Oettingen in Oettingen, she was his second wife. She brought a dowry of 14,000guilder into the marriage. In 1594, Barbara gave birth to a daughter named Jakobina, but she died that year. Countess Barbara of Oettingen studied alchemy intensively and is considered one of the most important women who worked in this field, she employed several alchemists and corresponded extensively on this subject with her nephew, Count Palatine of Sulzbach. Barbara performed numerous experiments for Emperor Rudolf II in his residence in Prague, until she was expelled from the court. Barbara died in Oettingen in 1618 was buried beside her husband in the Castle Church of St. Michael in Harburg.

Their tomb is decorated with a larger than life-size figure of the Countess at the side of her husband and his first wife. Franz Joseph Mone: Anzeiger für Kunde der deutschen Vorzeit, Artistisch-literarische Anstalt des Germanischen Museums, 1863, S. 357

1993–94 New Jersey Devils season

The 1993–94 New Jersey Devils season was the franchise's 20th season, twelfth in New Jersey. For the fourth consecutive season, the Devils qualified for the playoffs. In the playoffs, The Devils made it all the way to the Eastern Conference Final where they came within a game of advancing to the 1994 Stanley Cup Finals. Goaltender Martin Brodeur won the Calder Memorial Trophy as the NHL's top rookie and new coach Jacques Lemaire won the Jack Adams Award as the NHL's top coach; the New Jersey Devils opened the 1993–94 season with 7 consecutive wins. They finished second in goaltending, they set team records in wins and points. Captain Scott Stevens led the league in +/- with +53. During the regular season, the Devils allowed the fewest even-strength goals and had the fewest power-play opportunities. Note: No. = Division rank, CR = Conference rank, W = Wins, L = Losses, T = Ties, GF = Goals For, GA = Goals Against, Pts = Points Teams that qualified for the playoffs are highlighted in bold. Round 1 New Jersey Devils vs Buffalo Sabres New Jersey Wins Series 4-3 Round 2 New Jersey Devils vs Boston Bruins New Jersey Wins Series 4-2 Round 3 New Jersey Devils vs New York Rangers New Jersey Loses Series 4-3 ScoringGoaltending ScoringGoaltendingNote: GP = Games played.

1993–94 NHL season "1993-94 National Hockey League Standings". HockeyDB. Archived from the original on 11 October 2007. Retrieved 2007-10-12. "1993-94 New Jersey Devils player statistics". HockeyDB. Retrieved 2007-10-12

Dawson, North Dakota

Dawson is a city in Kidder County, North Dakota, United States. The population was 61 at the 2010 census. Dawson was laid out in 1882 by J. Dawson Thompson, named for him. A post office has been in operation at Dawson since 1881. Dawson is located at 46°52′2″N 99°45′9″W. According to the United States Census Bureau, the city has a total area of 0.34 square miles, all of it land. Dawson has a veteran's memorial wall to honor soldiers in foreign wars; as of the census of 2010, there were 61 people, 30 households, 16 families residing in the city. The population density was 179.4 inhabitants per square mile. There were 54 housing units at an average density of 158.8 per square mile. The racial makeup of the city was 100.0% White. Hispanic or Latino of any race were 8.2% of the population. There were 30 households of which 20.0% had children under the age of 18 living with them, 40.0% were married couples living together, 6.7% had a female householder with no husband present, 6.7% had a male householder with no wife present, 46.7% were non-families.

46.7% of all households were made up of individuals and 16.6% had someone living alone, 65 years of age or older. The average household size was 2.03 and the average family size was 2.75. The median age in the city was 52.5 years. 21.3% of residents were under the age of 18. The gender makeup of the city was 57.4% male and 42.6% female. As of the census of 2000, there were 75 people, 38 households, 16 families residing in the city; the population density was 186.9 people per square mile. There were 52 housing units at an average density of 129.6 per square mile. The racial makeup of the city was 100.00% White. There were 38 households out of which 18.4% had children under the age of 18 living with them, 31.6% were married couples living together, 2.6% had a female householder with no husband present, 55.3% were non-families. 52.6% of all households were made up of individuals and 36.8% had someone living alone, 65 years of age or older. The average household size was 1.97 and the average family size was 3.00.

In the city, the population was spread out with 20.0% under the age of 18, 9.3% from 18 to 24, 14.7% from 25 to 44, 25.3% from 45 to 64, 30.7% who were 65 years of age or older. The median age was 49 years. For every 100 females, there were 127.3 males. For every 100 females age 18 and over, there were 93.5 males. The median income for a household in the city was $20,833, the median income for a family was $22,917. Males had a median income of $23,750 versus $0 for females; the per capita income for the city was $13,192. There were no families and 20.3% of the population living below the poverty line, including no under eighteens and 23.3% of those over 64. Harker Lake Upper Harker Lake Dawson centennial 1880-1980: Dawson, North Dakota: the first 100 years from the Digital Horizons website

Different Strokes (The Nite-Liters album)

Different Strokes is the fourth album by the Louisville, Kentucky group The Nite-Liters, the instrumental ensemble offshoot of New Birth, featuring Tony Churchill, James Baker, Robin Russell, Austin Lander, Robert "Lurch" Jackson, Leroy Taylor, Charlie Hearndon. Released in 1972 on RCA Records. Produced by mentor Harvey Fuqua. "Do The Granny" 3:06 "Money Runner" 3:25 "Stop, Listen" 5:06 "Theme from Angela" 4:07 "Funky-Vamp" 5:03 "Maynard Ferguson's Theme" 5:51 "Theme from Buck & The Preacher" 4:03 "Back Down Home" 3:28 "Skimo's Theme" 4:41 Chi Ali sampled "Funky-Vamp" on his song "Chi-Ali vs. Vanilla Shake" on his debut album The Fabulous Chi-Ali in 1992. "Do the Granny" was used in DJ Shadow's Funky Skunk mix CD. The Nite-Liters-Different Strokes at Discogs