Metropolitan may refer to: A Metropolitan area, is a region consisting of a densely populated urban core and its less-populated surrounding territories Metropolitan borough, a form of local government district in England Metropolitan county, a type of county-level administrative division of England Metropolitan Corporation (Pakistan), a local government authority in Pakistan Businesses Metro-Cammell, previously the Metropolitan Cammell Carriage and Wagon Company Metropolitan-Vickers, a British heavy electrical engineering company Metropolitan Stores, a Canadian former department store chain Metropolitan Books, an imprint of Henry Holt and CompanyColleges and universities Leeds Metropolitan University, United Kingdom London Metropolitan University, United Kingdom Manchester Metropolitan University, United Kingdom Metropolitan Community College (Omaha), United States Metropolitan State University of Denver, United States Metro State Roadrunners...

The Madonna and Child with St. Anne, also known as Sant'Anna Metterza, is a painting of c. 1424-1425 by the Italian Renaissance painter Masaccio, probably in collaboration with Masolino da Panicale. The painting is in the Galleria degli Uffizi in Florence, Italy, and measures 175 centimetres high and 103 centimetres wide.The Virgin and Child, with its powerful volume and solid possession of space by means of an assured perspectival structure, is one of the earliest works credited to Masaccio. Except for one, the angels, very delicate in their tender forms and pale, gentle colouring, are from the more Gothic brush of Masolino; the angel in the upper right hand curve reveals the hand of Masaccio. The figure of St. Anne is much worn and hence to be judged with difficulty, but her hand, which seems to explore the depth of the picture-space, may well be an invention of Masaccio. Masaccio's work shows the influence of Donatello in its soft, rounded forms and realistic texture. The ‘Madonna and Child with Saint Anne’ was originally commissioned for the Sant’Ambrogio church in Florence. According to Vasari, “It was placed in the chapel door which...

The nucleus is the solid, central part of a comet, once termed a dirty snowball or an icy dirtball. A cometary nucleus is composed of rock, dust, and frozen gases. When heated by the Sun, the gases sublime and produce an atmosphere surrounding the nucleus known as the coma. The force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous tail to form, which points away from the Sun. A typical comet nucleus has an albedo of 0.04. This is blacker than coal, and may be caused by a covering of dust.Results from the Rosetta and Philae spacecraft show that the nucleus of 67P/Churyumov–Gerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals. Further, the ALICE spectrograph on Rosetta determined that electrons (within 1 km (0.62 mi) above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma. On 30 July 2015...

The thermal cycler (also known as a thermocycler, PCR machine or DNA amplifier) is a laboratory apparatus most commonly used to amplify segments of DNA via the polymerase chain reaction (PCR). Thermal cyclers may also be used in laboratories to facilitate other temperature-sensitive reactions, including restriction enzyme digestion or rapid diagnostics. The device has a thermal block with holes where tubes holding the reaction mixtures can be inserted. The cycler then raises and lowers the temperature of the block in discrete, pre-programmed steps. History The earliest thermal cyclers were designed for use with the Klenow fragment of DNA polymerase I. Since this enzyme is destroyed during each heating step of the amplification process, new enzyme had to be added every cycle. This led to a cumbersome machine based on an automated pipettor, with open reaction tubes. Later, the PCR process was adapted to the use of thermostable DNA polymerase from Thermus aquaticus, which greatly simplified the design of the thermal cycler. While in some old machines the block is submerged in an oil bath to...

Vapour-compression refrigeration or vapor-compression refrigeration system (VCRS), in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and is the most widely used method for air conditioning of buildings and automobiles. It is also used in domestic and commercial refrigerators, large-scale warehouses for chilled or frozen storage of foods and meats, refrigerated trucks and railroad cars, and a host of other commercial and industrial services. Oil refineries, petrochemical and chemical processing plants, and natural gas processing plants are among the many types of industrial plants that often utilize large vapor-compression refrigeration systems. Cascade refrigeration systems may also be implemented using two compressors. Refrigeration may be defined as lowering the temperature of an enclosed space by removing heat from that space and transferring it elsewhere. A device that performs this function may also be called an air conditioner, refrigerator, air source heat pump, geothermal heat pump, or chiller (heat pump). Description of the vapor...