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Solar sail

Solar sails are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors. Based on the physics, a number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. A useful analogy to solar sailing may be a sailing boat. High-energy laser beams could be used as an alternative light source to exert much greater force than would be possible using sunlight, a concept known as beam sailing. Solar sail craft offer the possibility of low-cost operations combined with long operating lifetimes. Since they have few moving parts and use no propellant, they can be used numerous times for delivery of payloads. Solar sails use a phenomenon. Solar pressure affects all spacecraft, whether in interplanetary space or in orbit around a planet or small body. A typical spacecraft going to Mars, for example, will be displaced thousands of kilometers by solar pressure, so the effects must be accounted for in trajectory planning, done since the time of the earliest interplanetary spacecraft of the 1960s.

Solar pressure affects the orientation of a spacecraft, a factor that must be included in spacecraft design. The total force exerted on an 800 by 800 meter solar sail, for example, is about 5 newtons at Earth's distance from the Sun, making it a low-thrust propulsion system, similar to spacecraft propelled by electric engines, but as it uses no propellant, that force is exerted constantly and the collective effect over time is great enough to be considered a potential manner of propelling spacecraft. Johannes Kepler observed that comet tails point away from the Sun and suggested that the Sun caused the effect. In a letter to Galileo in 1610, he wrote, "Provide ships or sails adapted to the heavenly breezes, there will be some who will brave that void." He might have had the comet tail phenomenon in mind when he wrote those words, although his publications on comet tails came several years later. James Clerk Maxwell, in 1861–1864, published his theory of electromagnetic fields and radiation, which shows that light has momentum and thus can exert pressure on objects.

Maxwell's equations provide the theoretical foundation for sailing with light pressure. So by 1864, the physics community and beyond knew sunlight carried momentum that would exert a pressure on objects. Jules Verne, in From the Earth to the Moon, published in 1865, wrote "there will some day appear velocities far greater than these, of which light or electricity will be the mechanical agent... we shall one day travel to the moon, the planets, the stars." This is the first published recognition that light could move ships through space. Pyotr Lebedev was first to demonstrate light pressure, which he did in 1899 with a torsional balance. Svante Arrhenius predicted in 1908 the possibility of solar radiation pressure distributing life spores across interstellar distances, providing one means to explain the concept of panspermia, he was the first scientist to state that light could move objects between stars. Konstantin Tsiolkovsky first proposed using the pressure of sunlight to propel spacecraft through space and suggested, "using tremendous mirrors of thin sheets to utilize the pressure of sunlight to attain cosmic velocities".

Friedrich Zander published a technical paper in 1925 that included technical analysis of solar sailing. Zander wrote of "applying small forces" using "light pressure or transmission of light energy to distances by means of thin mirrors". JBS Haldane speculated in 1927 about the invention of tubular spaceships that would take humanity to space and how "wings of metallic foil of a square kilometre or more in area are spread out to catch the Sun's radiation pressure". J. D. Bernal wrote in 1929, "A form of space sailing might be developed which used the repulsive effect of the Sun's rays instead of wind. A space vessel spreading its large, metallic wings, acres in extent, to the full, might be blown to the limit of Neptune's orbit. To increase its speed, it would tack, close-hauled, down the gravitational field, spreading full sail again as it rushed past the Sun."The first formal technology and design effort for a solar sail began in 1976 at Jet Propulsion Laboratory for a proposed mission to rendezvous with Halley's Comet.

Many people believe that spacecraft using solar sails are pushed by the Solar winds just as sailboats and sailing ships are pushed by the winds across the waters on Earth. But Solar radiation exerts a pressure on the sail due to reflection and a small fraction, absorbed; the momentum of a photon or an entire flux is given by Einstein's relation: p = E/cwhere p is the momentum, E is the energy, c is the speed of light. The momentum of a photon depends on its wavelength p = h/λ Solar radiation pressure can be related to the irradiance value of 1361 W/m2 at 1 AU, as revised in 2011: perfect absorbance: F = 4.54 μN per square metre in the direction of the incident beam perfect reflectance: F = 9.08 μN per square metre in the direction normal to surface An ideal sail is flat and has 100% specular reflection. An actual sail will have an overall efficiency of about 90%, about 8.17 μN/m2, due to curvature, absorbance, re-radiation from front and back, non-specular effects, other factors. The force on a sail and the actual

Soviet minesweeper T-115

T-115 was a minesweeper of the Soviet Navy during World War II and the Cold War. She had been built as USS Apex, an Admirable-class minesweeper, for the United States Navy during World War II, but never saw active service in the U. S. Navy. Upon completion she was transferred to the Soviet Union under Lend-Lease as T-115; the ship was scrapped on 1 June 1966. Because of the Cold War, the U. S. Navy was unaware of this fate and the vessel remained on the American Naval Vessel Register until she was struck on 1 January 1983. Apex was laid down on 8 June 1942 at Tampa, Florida, by the Tampa Shipbuilding Co.. She was transferred to the Soviet Navy that same day as T-115, she was never returned to U. S. custody. In Soviet service she was renamed Aydar on 1 September 1955, she was scrapped on 1 June 1966. Due to the ongoing Cold War, the U. S. Navy was unaware of this fate, they had reclassified the vessel as MSF-142 on 7 February 1955, kept her on the American Naval Vessel Register until she was struck on 1 January 1983.

This article incorporates text from the public domain Dictionary of American Naval Fighting Ships. NavSource Online: Mine Warfare Vessel Photo Archive – Apex – ex-AM-142 – ex-AMc-119


A plasmid is a small, extrachromosomal DNA molecule within a cell, physically separated from chromosomal DNA and can replicate independently. They are most found as small circular, double-stranded DNA molecules in bacteria. In nature, plasmids carry genes that benefit the survival of the organism and confer selective advantage such as antibiotic resistance. While chromosomes are large and contain all the essential genetic information for living under normal conditions, plasmids are very small and contain only additional genes that may be useful in certain situations or conditions. Artificial plasmids are used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms. In the laboratory, plasmids may be introduced into a cell via transformation. Plasmids are considered replicons, units of DNA capable of replicating autonomously within a suitable host. However, like viruses, are not classified as life. Plasmids are transmitted from one bacterium to another through conjugation.

This host-to-host transfer of genetic material is one mechanism of horizontal gene transfer, plasmids are considered part of the mobilome. Unlike viruses, which encase their genetic material in a protective protein coat called a capsid, plasmids are "naked" DNA and do not encode genes necessary to encase the genetic material for transfer to a new host; the size of the plasmid varies from 1 to over 200 kbp, the number of identical plasmids in a single cell can range anywhere from one to thousands under some circumstances. The term plasmid was introduced in 1952 by the American molecular biologist Joshua Lederberg to refer to "any extrachromosomal hereditary determinant." The term's early usage included any bacterial genetic material that exists extrachromosomally for at least part of its replication cycle, but because that description includes bacterial viruses, the notion of plasmid was refined over time to comprise genetic elements that reproduce autonomously. In 1968, it was decided that the term plasmid should be adopted as the term for extrachromosomal genetic element, to distinguish it from viruses, the definition was narrowed to genetic elements that exist or predominantly outside of the chromosome and can replicate autonomously.

In order for plasmids to replicate independently within a cell, they must possess a stretch of DNA that can act as an origin of replication. The self-replicating unit, in this case, the plasmid, is called a replicon. A typical bacterial replicon may consist of a number of elements, such as the gene for plasmid-specific replication initiation protein, repeating units called iterons, DnaA boxes, an adjacent AT-rich region. Smaller plasmids make use of the host replicative enzymes to make copies of themselves, while larger plasmids may carry genes specific for the replication of those plasmids. A few types of plasmids can insert into the host chromosome, these integrative plasmids are sometimes referred to as episomes in prokaryotes. Plasmids always carry at least one gene. Many of the genes carried by a plasmid are beneficial for the host cells, for example: enabling the host cell to survive in an environment that would otherwise be lethal or restrictive for growth; some of these genes encode traits for antibiotic resistance or resistance to heavy metal, while others may produce virulence factors that enable a bacterium to colonize a host and overcome its defences or have specific metabolic functions that allow the bacterium to utilize a particular nutrient, including the ability to degrade recalcitrant or toxic organic compounds.

Plasmids can provide bacteria with the ability to fix nitrogen. Some plasmids, have no observable effect on the phenotype of the host cell or its benefit to the host cells cannot be determined, these plasmids are called cryptic plasmids. Occurring plasmids vary in their physical properties, their size can range from small mini-plasmids of less than 1-kilobase pairs to large megaplasmids of several megabase pairs. At the upper end, little differs between a minichromosome. Plasmids are circular, but examples of linear plasmids are known; these linear plasmids require specialized mechanisms to replicate their ends. Plasmids may be present in an individual cell in varying number, ranging from one to several hundreds; the normal number of copies of plasmid that may be found in a single cell is called the Plasmid copy number, is determined by how the replication initiation is regulated and the size of the molecule. Larger plasmids tend to have lower copy numbers. Low-copy-number plasmids that exist only as one or a few copies in each bacterium are, upon cell division, in danger of being lost in one of the segregating bacteria.

Such single-copy plasmids have systems that attempt to distribute a copy to both daughter cells. These systems, which include the parABS system and parMRC system, are referred to as the partition system or partition function of a plasmid. Plasmids may be classified in a number of ways. Plasmids can be broadly classified into non-conjugative plasmids. Conjugative plasmids contain a set of transfer or tra genes which promote sexual conjugation between different cells. In the complex process of conjugation, plasmids may be transferred from one bacterium to another via sex pili encoded by some of the tra genes. Non-conjugative plasmids are incapable of initiating conjugation, hence they can be transferred only wit

Texas Panhandle

The Texas Panhandle is a region of the U. S. state of Texas consisting of the northernmost 26 counties in the state. The panhandle is a rectangular area bordered by New Mexico to the West and Oklahoma to the North and East; the Handbook of Texas defines the southern border of Swisher County as the southern boundary of the Texas Panhandle region. Its land area is nearly 10 % of the state's total; the Texas Panhandle is larger in size than the US state of West Virginia. An additional 62.75 sq mi is covered by water. Its population as of the 2010 census was 1.7 % of the state's total population. As of the 2010 census, the population density for the region was 16.6 per square mile. However, more than 72% of the Panhandle's residents live in the Amarillo Metropolitan Area, the largest and fastest-growing urban area in the region; the Panhandle is distinct from North Texas, further South-East. West of the Caprock Escarpment and North and South of the Canadian River breaks, the surface of the Llano Estacado is rather flat.

South of the city of Amarillo, the level terrain gives way to Palo Duro Canyon, the second-largest canyon in the United States. This colorful canyon was carved by the Prairie Dog Town Fork Red River. North of Amarillo lies a reservoir created by Sanford Dam on the Canadian River; the lake, along with the Ogallala Aquifer, provides drinking water and irrigation for this moderately dry area of the High Plains. Interstate Highway 40 passes through the Panhandle, passes through Amarillo; the freeway passes through Deaf Smith, Potter, Gray and Wheeler Counties. The Texas Panhandle has been identified in the early 21st century as one of the fastest-growing windpower-producing regions in the nation because of its strong, steady winds. Before the rise of Amarillo, the three original towns of the Panhandle were Clarendon in Donley County, Mobeetie in Wheeler County, Tascosa in Oldham County. Clarendon moved itself after it was overlooked by the Fort Denver Railroad. Mobeetie was reduced below its original small size with the closure of the United States Army's Fort Elliott in 1890.

Tascosa was ruined by the location of the railroad too far North of the town and the inability to build a feeder line. The Tascosa Pioneer wrote in 1890: "Truly this is a world which has no regard for the established order of things but knocks them sky west and crooked, lo, the upstart hath the land and its fatness." As of the census of 2000, about 402,862 people lived in the Panhandle. Of these, 68.9% were non-Hispanic White, 23.8% were Hispanic, 4.6% were African American. Only 2.7% were of some other ethnicity. About 92.3% of inhabitants claimed native birth, 8.9% were veterans of the United States armed forces. Around 13.2% of the population was 65 years of age or older, whereas 27.8% of the population was under 18 years of age. The 26 northernmost counties that make up the Texas Panhandle include: Major cities of the Texas Panhandle with populations greater than 10,000 include: Some of the smaller towns with populations less than 10,000 include: Much like the rest of West Texas and the Oklahoma Panhandle, the region is politically and conservative.

Following the pattern of other larger cities, Amarillo has the largest liberal population in the Panhandle. It was one of the first regions of the state to break away from its Democratic roots, though Democrats continued to do well at the local level well into the 1980s. However, Republicans now dominate every level of government, holding nearly every elected post above the county level. Nearly all of the Panhandle is in Texas's 13th congressional district, represented by Republican Mac Thornberry. With a Cook Partisan Voting Index of R+33, it is the most Republican district in the nation; the counties of Castro and Parmer are in Texas's 19th congressional district, represented by Republican Jodey Arrington. In the 2016 Presidential election, Donald Trump received 79.9% of the vote in the 13th District, as compared with Hillary Clinton's 16.9% share of the vote. Panhandle from the Handbook of Texas Online Photos of the Llano Estacado

Bill Daniel

William Partlow Daniel, was the fifth Appointed Governor of Guam served from 1961 to 1963 and Democratic member of the Texas House of Representatives. Born in Dayton, a graduate of Baylor University and a member of the Baylor University Chamber of Commerce, he spent the majority of his life working as a lawyer in Liberty County, Texas. Bill Daniel was born into a wealthy and prominent Texas family, his older brother Price Daniel Sr. went on to become Governor of Texas, Texas Supreme Court Justice and a US Senator. Daniel made large donations to good causes to his alma mater Baylor University, several of the campus buildings are named after him, his late wife Vara and other members of the Daniel family. From 1949 to 1953 he served as a Democratic Party member of the Texas House of Representatives for the 14th District, his brother Price had held this office from 1939 - 1945. In 1961, U. S. President John F. Kennedy appointed him to the position of governor of Guam, an office that he held from May 20, 1961 to January 20, 1963.

His main achievement as Governor was to arrange for the removal of the requirement of a "security clearance" to enter or leave Guam, by persuading Kennedy to sign an Executive Order, rescinding the one put in place during 1941 by President Franklin D. Roosevelt; the old travel restrictions required that all civilians wishing to visit Guam needed to obtain approval from a senior US Navy officer based in Washington, D. C.. This was an obstacle to development in the area of tourism, its removal benefited the economy of the territory, his appointment resulted in the first occasion in which brothers held governorships in the United States, as his older brother Price was governor of Texas for the entire time of his service as governor of Guam. Bill Daniel was married to Vara Faye Martin and have four children - Will, Ann and Dani. Bill Daniel appeared in the John Wayne film The Alamo playing Colonel Neill. Daniel provided the film with 400 longhorns and hundreds of horses from his ranch. Daniel's most memorable scene from the film is suggesting a courier named Smitty, played by Frankie Avalon, dismount for food and rest, which Smitty refuses in order to return to help defend the Alamo.

Bill Daniel died on June 20, 2006 at his home in Liberty, Texas at the age of 90. Legislative Reference Library of Texas. Bill Daniel on IMDb Bill Daniel at Find a Grave

Quake Minus One

Quake Minus One is a real-time strategy video game published for the Commodore 64 by Monolith/Beyond in 1985 and was written by Warren Foulkes and Mike Singleton. In the 1980s, the Western world constructed a large power plant named Titan under the Atlantic Ocean in order to extract geothermal energy from the Mid-Atlantic Ridge where the Earth's crust is thinnest; the power plant is operated and maintained by robots. Members of the Robot Liberation Front invade the power plant and seize control of the robots demanding equal rights for the machines, failing which they would use the power plant to trigger a massive earthquake which would threaten America and Africa. Titan is under the control of five separate computers - Zeus, Vulcan and Hermes and scientists have managed to regain control of Hermes and the robots it operates, it is up to these robots to regain control of the other four computers who are moving to regain control. The action begins with the player in control with a randomly placed Hermes controlled robot.

The AI is maneuvering its robots to take control of Hermes so it is up to the player to maneuver their robots and formulate a strategy to retake control of the wayward computers. The player does have one advantage - he can enter into the map mode which will pause the game allowing a brief respite from the action and a chance to view a detailed map of the Titan installation; as robots travel down roads, they may come to roads controlled by other computers where they will be attacked by fixed installations such as bunkers. Robots that have ion cannons can capture roads and junctions putting them under the control of Hermes. Once a computer is captured, all its remaining robots are passed to the control of Hermes. There are quake suppression buildings to protect which if destroyed, bring forward the game's deadline. Zzap!64 found the game confusing with unclear instructions and a disappointment following pre-release publicity. It was given an overall score of 67%