The term stained glass can refer to coloured glass as a material or to works created from it. Throughout its thousand-year history, the term has been applied exclusively to the windows of churches and other significant religious buildings. Although traditionally made in flat panels and used as windows, the creations of modern stained glass artists include three-dimensional structures and sculpture. Modern vernacular usage has extended the term "stained glass" to include domestic lead light and objects d'art created from foil glasswork exemplified in the famous lamps of Louis Comfort Tiffany; as a material stained glass is glass, coloured by adding metallic salts during its manufacture. The coloured glass is crafted into stained glass windows in which small pieces of glass are arranged to form patterns or pictures, held together by strips of lead and supported by a rigid frame. Painted details and yellow stain are used to enhance the design; the term stained glass is applied to windows in which the colours have been painted onto the glass and fused to the glass in a kiln.
Stained glass, as an art and a craft, requires the artistic skill to conceive an appropriate and workable design, the engineering skills to assemble the piece. A window must fit snugly into the space for which it is made, must resist wind and rain, especially in the larger windows, must support its own weight. Many large windows have withstood the test of time and remained intact since the Late Middle Ages. In Western Europe they constitute the major form of pictorial art to have survived. In this context, the purpose of a stained glass window is not to allow those within a building to see the world outside or primarily to admit light but rather to control it. For this reason stained glass windows have been described as "illuminated wall decorations"; the design of a window may be figurative. Windows within a building may be thematic, for example: within a church – episodes from the life of Christ. Stained glass is still popular today, but referred to as art glass, it is prevalent in luxury homes, commercial buildings, places of worship.
Artists and companies are contracted to create beautiful art glass ranging from domes, backsplashes, etc. During the late medieval period, glass factories were set up where there was a ready supply of silica, the essential material for glass manufacture. Silica requires a high temperature to melt, something not all glass factories were able to achieve; such materials as potash and lead can be added to lower the melting temperature. Other substances, such as lime, are added to rebuild the weakened network and make the glass more stable. Glass is coloured by adding metallic oxide powders or finely divided metals while it is in a molten state. Copper oxides produce green or bluish green, cobalt makes deep blue, gold produces wine red and violet glass. Much modern red glass is produced using copper, less expensive than gold and gives a brighter, more vermilion shade of red. Glass coloured while in the clay pot in the furnace is known as pot metal glass, as opposed to flashed glass. Using a blow-pipe, a "gather" of molten glass is taken from the pot heating in the furnace.
The gather is formed to a bubble of air blown into it. Using metal tools, molds of wood that have been soaking in water, gravity, the gather is manipulated to form a long, cylindrical shape; as it cools, it is reheated. During the process, the bottom of the cylinder is removed. Once brought to the desired size it is left to cool. One side of the cylinder is opened, it is put into another oven to heat and flatten it, placed in an annealer to cool at a controlled rate, making the material more stable. "Hand-blown" cylinder and crown glass were the types used in ancient stained-glass windows. Stained glass windows were in churches and chapels as well as many more well respected buildings; this hand-blown glass is created by blowing a bubble of air into a gather of molten glass and spinning it, either by hand or on a table that revolves like a potter's wheel. The centrifugal force causes the molten bubble to flatten, it can be cut into small sheets. Glass formed this way can be either coloured and used for stained-glass windows, or uncoloured as seen in small paned windows in 16th- and 17th-century houses.
Concentric, curving waves are characteristic of the process. The center of each piece of glass, known as the "bull's-eye", is subject to less acceleration during spinning, so it remains thicker than the rest of the sheet, it has the distinctive lump of glass left by the "pontil" rod, which holds the glass as it is spun out. This lumpy, refractive quality means the bulls-eyes are less transparent, but they have still been used for windows, both domestic and ecclesiastical. Crown glass is still made today, but not on a large scale. Rolled glass is produced by pouring molten glass onto a metal or graphite table and rolling it into a sheet using a large metal cylinder, similar to rolling out a pie crust; the rolling can be done by machine. Glass can be "double rolled", which means it is passed through two cylinders at once to yield glass of a specified thickness (typically about 1/8" or
A curator is a manager or overseer. Traditionally, a curator or keeper of a cultural heritage institution is a content specialist charged with an institution's collections and involved with the interpretation of heritage material. A traditional curator's concern involves tangible objects of some sort — artwork, historic items, or scientific collections. More new kinds of curators have started to emerge: curators of digital data objects and biocurators. In smaller organizations, a curator may have sole responsibility for acquisitions and for collections care; the curator makes decisions regarding what objects to select, oversees their potential and documentation, conducts research based on the collection and its history, provides proper packaging of art for transportation, shares research with the public and community through exhibitions and publications. In small, volunteer-based museums such as those of local historical societies, a curator may be the only paid staff-member. In larger institutions, the curator's primary function is that of a subject specialist, with the expectation that he or she will conduct original research on objects and guide the organization in its collecting.
Such institutions can have multiple curators, each assigned to a specific collecting area and operating under the direction of a head curator. In such organizations, the physical care of the collection may be overseen by museum collections-managers or by museum conservators, with documentation and administrative matters handled by a museum registrar. In the United Kingdom, the term "curator" applies to government employees who monitor the quality of contract archaeological work under Planning Policy Guidance 16: Archaeology and Planning and manage the cultural resource of a region. In the museum setting, a curator in the United Kingdom may be called a "keeper". In Scotland, the term "curator" is used to mean the guardian of a child, known as curator ad litem. In the US, curators have multifaceted tasks dependent on its mission, but in recent years the role of the curator has evolved alongside the changing role of museums. As US museums have become more digitized, curators find themselves constructing narratives in both the material and digital worlds.
Historian Elaine Gurian has called for museums in which "visitors could comfortably search for answers to their own questions regardless of the importance placed on such questions by others". This would change the role of curator from teacher to "facilitator and assistor". In this sense, the role of curator in the United States is precarious, as digital and interactive exhibits allow members of the public to become their own curators, to choose their own information. Citizens are able to educate themselves on the specific subject they are interested in, rather than spending time listening to information they have no desire to learn. More advances in new technologies have led to a further widening of the role of curator; this has been a focus in major art institutions internationally and has become an object of academic study and research. In contemporary art, the title "curator" identifies a person who selects and interprets works of art. In addition to selecting works, the curator is responsible for writing labels, catalog essays, other content supporting exhibitions.
Such curators may be permanent staff members, "guest curators" from an affiliated organization or university, or "freelance curators" working on a consultancy basis. The late-20th century saw an explosion of artists organizing exhibitions; the artist-curator has a long tradition of influence, notably featuring Sir Joshua Reynolds, inaugural president of the Royal Academy of Arts, founded in 1768. In some US cultural organizations, the term "curator" may designate the head of any given division; this has led to the proliferation of titles such as "Curator of Education" and "Curator of Exhibitions". The term "literary curator" has been used to describe persons who work in the field of poetry, such as former 92nd Street Y poetry-director Karl Kirchwey; this trend has been mirrored in the United Kingdom in such institutions as Ikon, Birmingham, UK and Baltic, Gateshead, UK. In Australia and New Zealand, the term applies to a person who prepares a sports ground for use; this job is equivalent to that of groundsman in some other cricketing nations.
In France, the term curator is translated as conservateur. There are two kinds of curators: heritage curators with five specialities, librarian curators; these curators are selected by competitive examination and attend the INP. The "conservateurs du patrimoine" are civil servants or work in the public service. Curators hold a high academic degree in their subject a Doctor of Philosophy or a master's degree in subjects such as history, history of art, archaeology, anthropology, or classics. Curators are expected to have contributed to their academic field, for example, by delivering public talks, publishing articles, or presenting at specialist academic conferences, it is important that curators have knowledge of the current collecting market for their area of expertise, are aware of current ethical practices and laws that may impact their organisation's collecting. The increa
The goth subculture is a subculture that began in England during the early 1980s, where it developed from the audience of gothic rock, an offshoot of the post-punk genre. The name, goth subculture, derived directly from the music genre. Notable post-punk groups that presaged that genre and helped develop and shape the subculture, include Siouxsie and the Banshees, Joy Division and The Cure; the goth subculture has survived much longer than others of the same era, has continued to diversify and spread throughout the world. Its imagery and cultural proclivities indicate influences from 19th-century Gothic literature and gothic horror films; the scene is centered on music festivals and organized meetings in Western Europe. The goth subculture has associated tastes in music and fashion; the music preferred by the goth subculture includes a number of different styles, e.g. gothic rock, death rock, post-punk, cold wave, dark wave, ethereal wave. Styles of dress within the subculture draw on punk, new wave and new romantic fashion as well as fashion of earlier periods such as the Victorian and Edwardian eras, or combinations of the above.
The style includes dark attire, pale face makeup and black hair. The subculture continues to draw interest from a large audience decades after its emergence; the term "gothic rock" was coined in 1967, by music critic John Stickney to describe a meeting he had with Jim Morrison in a dimly lit wine-cellar which he called "the perfect room to honor the Gothic rock of the Doors". That same year, Velvet Underground with a track like "All Tomorrow's Parties", created a kind of "mesmerizing gothic-rock masterpiece" according to music historian Kurt Loder. In the late 1970s, the "gothic" adjective was used to describe the atmosphere of post-punk bands like Siouxsie and the Banshees and Joy Division. In a live review about a Siouxsie and the Banshees' concert in July 1978, critic Nick Kent wrote that concerning their music, "parallels and comparisons can now be drawn with gothic rock architects like the Doors and early Velvet Underground". In March 1979, in his review of Magazine's second album Secondhand Daylight, Kent noted that there was "a new austere sense of authority" in the music, with a "dank neo-Gothic sound".
That year, the term was used by Joy Division's manager, Tony Wilson on 15 September in an interview for the BBC TV programme's Something Else. Wilson described Joy Division as "gothic" compared to the pop mainstream, right before a live performance of the band; the term was applied to "newer bands such as Bauhaus who had arrived in the wake of Joy Division and Siouxsie and the Banshees". Bauhaus's first single issued in 1979, "Bela Lugosi's Dead", is credited as the starting point of the gothic rock genre. In 1979, Sounds described Joy Division as "Gothic" and "theatrical". In February 1980, Melody Maker qualified the same band as "masters of this Gothic gloom". Critic Jon Savage would say that their singer Ian Curtis wrote "the definitive Northern Gothic statement". However, it was not until the early-1980s that gothic rock became a coherent music subgenre within post-punk, that followers of these bands started to come together as a distinctly recognizable movement, they may have taken the "goth" mantle from a 1981 article published in UK rock weekly Sounds: "The face of Punk Gothique", written by Steve Keaton.
In a text about the audience of UK Decay, Keaton asked: "Could this be the coming of Punk Gothique? With Bauhaus flying in on similar wings could it be the next big thing?" In July 1982, the opening of the Batcave in London's Soho provided a prominent meeting point for the emerging scene, which would be labelled "positive punk" by the NME in a special issue with a front cover in early 1983. The term "Batcaver" was used to describe old-school goths. Independent from the British scene, in the late 1970s and early 1980s in California, deathrock developed as a distinct branch of American punk rock, with acts such as Christian Death and 45 Grave; the bands that defined and embraced the gothic rock genre included Bauhaus, early Adam and the Ants, the Cure, the Birthday Party, Southern Death Cult, Sex Gang Children, UK Decay, Virgin Prunes, Killing Joke, the Damned. Near the peak of this first generation of the gothic scene in 1983, The Face's Paul Rambali recalled that there were "several strong Gothic characteristics" in the music of Joy Division.
In 1984, Joy Division's bassist Peter Hook named Play Dead as one of their heirs: "If you listen to a band like Play Dead, who I like, Joy Division played the same stuff that Play Dead are playing. They're similar." By the mid-1980s, bands began proliferating and became popular, including the Sisters of Mercy, the Mission, Alien Sex Fiend, the March Violets, Xmal Deutschland, the Membranes, Fields of Nephilim. Record labels like Factory, 4AD and Beggars Banquet released much of this music in Europe, through a vibrant import music market in the US, the subculture grew in New York and Los Angeles, where many nightclubs featured "gothic/industrial" nights; the popularity of 4AD bands resulted in the creation of a similar US label, which produces what was colloquially termed ethereal wave, a subgenre of dark wave music. The 1990s saw further growth for some 1980s bands and the emergence of many new acts, as well as new goth-centric U. S. record labels such as Cleopatra Records, among others. According to Dave Simpson of The Guardian, "in the 90s, goths all but disappeared as dance music became the dominant youth cult".
As a result, the goth "movement went underground and mistaken for cyber goth, Shock rock, Industrial metal, Gothic metal, Medieval folk metal and the latest sub
Laser cutting is a technology that uses a laser to cut materials, is used for industrial manufacturing applications, but is starting to be used by schools, small businesses, hobbyists. Laser cutting works by directing the output of a high-power laser most through optics; the laser optics and CNC are used to direct the laser beam generated. A typical commercial laser for cutting materials involved a motion control system to follow a CNC or G-code of the pattern to be cut onto the material; the focused laser beam is directed at the material, which either melts, vaporizes away, or is blown away by a jet of gas, leaving an edge with a high-quality surface finish. Industrial laser cutters are used to cut flat-sheet material as well as structural and piping materials. In 1965, the first production laser cutting machine was used to drill holes in diamond dies; this machine was made by the Western Electric Engineering Research Center. In 1967, the British pioneered laser-assisted oxygen jet cutting for metals.
In the early 1970s, this technology was put into production to cut titanium for aerospace applications. At the same time CO2 lasers were adapted to cut non-metals, such as textiles, because, at the time, CO2 lasers were not powerful enough to overcome the thermal conductivity of metals. Generation of the laser beam involves stimulating a lasing material by electrical discharges or lamps within a closed container; as the lasing material is stimulated, the beam is reflected internally by means of a partial mirror, until it achieves sufficient energy to escape as a stream of monochromatic coherent light. Mirrors or fiber optics are used to direct the coherent light to a lens, which focuses the light at the work zone; the narrowest part of the focused beam is less than 0.0125 inches. In diameter. Depending upon material thickness, kerf widths as small as 0.004 inches are possible. In order to be able to start cutting from somewhere other than the edge, a pierce is done before every cut. Piercing involves a high-power pulsed laser beam which makes a hole in the material, taking around 5–15 seconds for 0.5-inch-thick stainless steel, for example.
The parallel rays of coherent light from the laser source fall in the range between 0.06–0.08 inches in diameter. This beam is focused and intensified by a lens or a mirror to a small spot of about 0.001 inches to create a intense laser beam. In order to achieve the smoothest possible finish during contour cutting, the direction of beam polarization must be rotated as it goes around the periphery of a contoured workpiece. For sheet metal cutting, the focal length is 1.5–3 inches. Advantages of laser cutting over mechanical cutting include easier workholding and reduced contamination of workpiece. Precision may be better. There is a reduced chance of warping the material, being cut, as laser systems have a small heat-affected zone; some materials are very difficult or impossible to cut by more traditional means. Laser cutting for metals has the advantages over plasma cutting of being more precise and using less energy when cutting sheet metal. Newer laser machines operating at higher power are approaching plasma machines in their ability to cut through thick materials, but the capital cost of such machines is much higher than that of plasma cutting machines capable of cutting thick materials like steel plate.
There are three main types of lasers used in laser cutting. The CO2 laser is suited for cutting and engraving; the neodymium and neodymium yttrium-aluminium-garnet lasers are identical in style and differ only in application. Nd is used for boring; the Nd:YAG laser is used where high power is needed and for boring and engraving. Both CO2 and Nd/Nd:YAG lasers can be used for welding. CO2 lasers are "pumped" by passing a current through the gas mix or using radio frequency energy; the RF method has become more popular. Since DC designs require electrodes inside the cavity, they can encounter electrode erosion and plating of electrode material on glassware and optics. Since RF resonators have external electrodes they are not prone to those problems. CO2 lasers are used for industrial cutting of many materials including titanium, stainless steel, mild steel, plastic, engineered wood, wax and paper. YAG lasers are used for cutting and scribing metals and ceramics. In addition to the power source, the type of gas flow can affect performance as well.
Common variants of CO2 lasers include fast axial flow, slow axial flow, transverse flow, slab. In a fast axial flow resonator, the mixture of carbon dioxide and nitrogen is circulated at high velocity by a turbine or blower. Transverse flow lasers circulate the gas mix at a lower velocity. Slab or diffusion cooled resonators have a static gas field that requires no pressurization or glassware, leading to savings on replacement turbines and glassware; the laser generator and external optics require cooling. Depending on system size and configuration, waste heat may be transferred by a coolant or directly to air. Water is a used coolant circulated through a chiller or heat transfer system. A laser mi
Système universitaire de documentation
The système universitaire de documentation or SUDOC is a system used by the libraries of French universities and higher education establishments to identify and manage the documents in their possession. The catalog, which contains more than 10 million references, allows students and researcher to search for bibliographical and location information in over 3,400 documentation centers, it is maintained by the Bibliographic Agency for Higher Education. Official website
A useless machine is a device which has a function but no direct purpose. It may be intended to make a philosophical point, as an amusing engineering "hack", or as an intellectual joke. Devices which have no function or which malfunction are not considered to be "useless machines"; the most well-known "useless machines" are those inspired by Marvin Minsky's design, in which the device's sole function is to switch itself off by operating its own "off" switch. More elaborate devices and novelty toys, having some obvious function or entertainment value, have been based on these simple "useless machines"; the Italian artist Bruno Munari began building "useless machines" in the 1930s. He was a "third generation" Futurist and did not share the first generation's boundless enthusiasm for technology, but sought to counter the threats of a world under machine rule by building machines that were artistic and unproductive; the version of the useless machine that became famous in information theory appears to have been invented by MIT professor and artificial intelligence pioneer Marvin Minsky, while he was a graduate student at Bell Labs in 1952.
Minsky dubbed his invention the "ultimate machine". The device has been called the "Leave Me Alone Box". Minsky's mentor at Bell Labs, information theory pioneer Claude Shannon, made his own versions of the machine, he kept one on his desk. Clarke wrote, "There is something unspeakably sinister about a machine that does nothing—absolutely nothing—except switch itself off", he was fascinated by the concept. Minsky invented a "gravity machine" that would ring a bell if the gravitational constant were to change, a theoretical possibility, not expected to occur in the foreseeable future. In the 1960s, a novelty toy maker called "Captain Co." sold a "Monster Inside the Black Box", featuring a mechanical hand that emerged from a featureless plastic black box and flipped a toggle switch, turning itself off. This version may have been inspired in part by "Thing", the disembodied hand featured in the television sitcom The Addams Family. Other versions have been produced. In their conceptually purest form, these machines do nothing.
It is claimed that Don Poynter, who graduated from the University of Cincinnati in 1949 and founded Poynter Products, Inc. first produced and sold the "Little Black Box", which switched itself off. He added the coin snatching feature, dubbed his invention "The Thing", arranged licensing with the producers of the television show, The Addams Family, sold "Uncle Fester's Mystery Light Bulb" as another show spinoff product. Robert J. Whiteman and president of Liberty Library Corporation claims credit for developing "The Thing".. Both the plain black box and the bank version were sold by Spencer Gifts, appeared in its mail-order catalogs through the 1960s and early 1970s; as of 2015, a version of the coin snatching black box is being sold as the "Black Box Money Trap Bank" or "Black Box Bank". Do-it-yourself versions of the useless machine have been featured in a number of web videos and inspired more complex machines that are able to move or which use more than one switch; as of 2015, there are several completed or kit form devices being offered for sale.
In 2009, the artist David Moises exhibited his reconstruction of The Ultimate Machine aka Shannon's Hand, explained the interactions of Claude Shannon, Marvin Minsky, Arthur C. Clarke regarding the device. Episode 3 of the third season of the FX show Fargo, "The Law of Non-Contradiction", features a useless machine. Arthur Ganson Theo Jansen Bruno Munari Jean Tinguely Trammel of Archimedes Discard protocol Mechanical bank Rube Goldberg machine
A Möbius strip, Möbius band, or Möbius loop spelled Mobius or Moebius, is a surface with only one side and only one boundary. The Möbius strip has the mathematical property of being unorientable, it can be realized as a ruled surface. Its discovery is attributed to the German mathematicians August Ferdinand Möbius and Johann Benedict Listing in 1858, though a structure similar to the Möbius strip can be seen in Roman mosaics dated circa 200–250 AD. An example of a Möbius strip can be created by taking a paper strip and giving it a half-twist, joining the ends of the strip to form a loop. However, the Möbius strip is not a surface of only one exact size and shape, such as the half-twisted paper strip depicted in the illustration. Rather, mathematicians refer to the closed Möbius band as any surface, homeomorphic to this strip, its boundary is a simple closed curve, i.e. homeomorphic to a circle. This allows for a wide variety of geometric versions of the Möbius band as surfaces each having a definite size and shape.
For example, any rectangle can be glued to itself to make a Möbius band. Some of these can be smoothly modeled in Euclidean space, others cannot. A half-twist clockwise gives an embedding of the Möbius strip different from that of a half-twist counterclockwise – that is, as an embedded object in Euclidean space, the Möbius strip is a chiral object with right- or left-handedness. However, the underlying topological spaces within the Möbius strip are homeomorphic in each case. An infinite number of topologically different embeddings of the same topological space into three-dimensional space exist, as the Möbius strip can be formed by twisting the strip an odd number of times greater than one, or by knotting and twisting the strip, before joining its ends; the complete open Möbius band is an example of a topological surface, related to the standard Möbius strip, but, not homeomorphic to it. Finding algebraic equations, the solutions of which have the topology of a Möbius strip, is straightforward, but, in general, these equations do not describe the same geometric shape that one gets from the twisted paper model described above.
In particular, the twisted paper model is a developable surface. A system of differential-algebraic equations that describes models of this type was published in 2007 together with its numerical solution; the Euler characteristic of the Möbius strip is zero. The Möbius strip has several curious properties. A line drawn starting from the seam at the other side. If continued, the line meets the starting point, is double the length of the original strip; this single continuous curve demonstrates. Cutting a Möbius strip along the center line with a pair of scissors yields one long strip with two full twists in it, rather than two separate strips; this happens because the original strip only has one edge, twice as long as the original strip. Cutting creates a second independent edge, half of, on each side of the scissors. Cutting this new, strip down the middle creates two strips wound around each other, each with two full twists. If the strip is cut along about a third of the way in from the edge, it creates two strips: One is a thinner Möbius strip – it is the center third of the original strip, comprising one-third of the width and the same length as the original strip.
The other is a longer but thin strip with two full twists in it – this is a neighborhood of the edge of the original strip, it comprises one-third of the width and twice the length of the original strip. Other analogous strips can be obtained by joining strips with two or more half-twists in them instead of one. For example, a strip with three half-twists, when divided lengthwise, becomes a twisted strip tied in a trefoil knot. A strip with N half-twists, when bisected, becomes a strip with N + 1 full twists. Giving it extra twists and reconnecting the ends produces figures called paradromic rings. One way to represent the Möbius strip as a subset of three-dimensional Euclidean space is using the parametrization: x = cos u y = sin u z = v 2 sin u 2 where 0 ≤ u < 2 π and − 1 ≤ v ≤ 1. This creates a Möbius strip of width 1 whose center circle has radius 1, lies in the x y -plane and is centered at; the parameter u runs around th