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Batterie de cuisine	Batterie de cuisine	The batterie de cuisine (French; literally, kitchen artillery, i.e., kitchenware) is the range of tools and pans used in a professional kitchen. It includes the knives, frying pans, bakeware and the complete set of kitchen utensils required for cooking and for the making of desserts, pastries and confectionery. It does not include any of the fixed equipment such as cooking ranges, refrigeration equipment, etc.
Vestibular fold	Vestibular fold	The vestibular fold (ventricular fold, superior or false vocal cord) is one of two thick folds of mucous membrane, each enclosing a narrow band of fibrous tissue, the vestibular ligament, which is attached in front to the angle of the thyroid cartilage immediately below the attachment of the epiglottis, and behind to the antero-lateral surface of the arytenoid cartilage, a short distance above the vocal process.
Vestibular fold	Vestibular fold	The lower border of this ligament, enclosed in mucous membrane, forms a free crescentic margin, which constitutes the upper boundary of the ventricle of the larynx. They are lined with respiratory epithelium, while true vocal cords have stratified squamous epithelium.
Vestibular fold	Function	The vestibular folds of the larynx play a significant role in the maintenance of the laryngeal functions of breathing and preventing food and drink from entering the airway during swallowing. They aid phonation (speech) by suppressing dysphonia. In some ethnic singing and chanting styles, such as in Tuva, Sardinia, Mongolia, South Africa and Tibet (...) the vestibular folds may be used in co-oscillation with the vocal folds, producing very low or high pitched sounds(most of the time, one octave higher). Conversely, people who have had their epiglottis removed because of cancer do not choke any more than when it was present.
Vestibular fold	Society and culture	They have a minimal role in normal phonation, but are often used to produce deep sonorous tones in Tuvan throat singing, as well as in musical screaming and the death growl singing style used in various forms of metal. Simultaneous voicing with the vocal and vestibular folds is diplophonia. Some voice actors occasionally employ small amounts of this phonation for its dark, growling quality while portraying a "villainous" or antagonistic voice.
Touch guitar	Touch guitar	The touch guitar is a stringed instrument of the guitar family which has been designed to use a fretboard-tapping playing style. Touch guitars are meant to be touched or tapped, not strummed.
Touch guitar	History	The touch or tapping technique was formally codified by American guitarist Jimmie Webster in his 1952 method book called the Illustrated Touch System.
Touch guitar	History	Webster credited pickup designer Harry DeArmond with first demonstrating the potential for touch-style playing. Webster himself collaborated with Gretsch Guitars on a guitar stereo pickup design for the Touch System (which fed the bass and melody output to two separate amplifiers), but the concept was not commercially successful.Unlike Webster's approach, which was to play on a single-necked instrument, guitarist and luthier Dave Bunker designed, built, and patented (in 1961) the first double-necked, headless, touch-tapping instrument called the DuoLectar. While both guitars employed a two-handed tapping technique, Webster used a single-necked instrument while Bunker used his double-necked DuoLectar guitar.Webster's tapping technique can be heard on a 1959 record. In 1960, Bunker first demonstrated his double-necked instrument for the Portland Oregonian newspaper, and then on the nationally broadcast television show Ozark Jubilee. His designs ultimately led to his double-necked touch guitar in 1975.Other designs followed. Among them was the single-neck Chapman Stick (developed by Emmett Chapman in 1970 and produced in 1974), the single-neck Warr Guitar (first produced in 1991) and the single-neck Mobius Megatar. Other touch guitars have included the Solene, Chuck Soupios's dual-necked BiAxe (patented in 1980 and produced during the early 1980s), and Sergio Santucci's TrebleBass.
Touch guitar	History	Merle Travis occasionally used a tapping style on his single-neck, strummed guitar, as did Roy Smeck, George Van Eps, Barney Kessel and Harvey Mandell. Subsequent years have seen Eddie Van Halen, Stanley Jordan, Steve Vai, Jeff Healey, Fred Frith, Hans Reichel, Elliott Sharp, and Markus Reuter all feature the use of tapping techniques.
Waterproofing	Waterproofing	Waterproofing is the process of making an object or structure waterproof or water-resistant so that it remains relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environments or underwater to specified depths. Water-resistant and waterproof often refer to resistance to penetration of water in its liquid state and possibly under pressure, whereas damp proof refers to resistance to humidity or dampness. Permeation of water vapour through a material or structure is reported as a moisture vapor transmission rate (MVTR). The hulls of boats and ships were once waterproofed by applying tar or pitch. Modern items may be waterproofed by applying water-repellent coatings or by sealing seams with gaskets or o-rings. Waterproofing is used in reference to building structures (such as basements, decks, or wet areas), watercraft, canvas, clothing (raincoats or waders), electronic devices and paper packaging (such as cartons for liquids).
Waterproofing	In construction	In construction, a building or structure is waterproofed with the use of membranes and coatings to protect contents and structural integrity. The waterproofing of the building envelope in construction specifications is listed under 07 - Thermal and Moisture Protection within MasterFormat 2004, by the Construction Specifications Institute, and includes roofing and waterproofing materials.In building construction, waterproofing is a fundamental aspect of creating a building envelope, which is a controlled environment. The roof covering materials, siding, foundations, and all of the various penetrations through these surfaces must be water-resistant and sometimes waterproof. Roofing materials are generally designed to be water-resistant and shed water from a sloping roof, but in some conditions, such as ice damming and on flat roofs, the roofing must be waterproof. Many types of waterproof membrane systems are available, including felt paper or tar paper with asphalt or tar to make a built-up roof, other bituminous waterproofing, ethylene propylene diene monomer EPDM rubber, hypalon, polyvinyl chloride, liquid roofing, and more.
Waterproofing	In construction	Walls are not subjected to standing water, and the water-resistant membranes used as housewraps are designed to be porous enough to let moisture escape. Walls also have vapor barriers or air barriers. Damp proofing is another aspect of waterproofing. Masonry walls are built with a damp-proof course to prevent rising damp, and the concrete in foundations needs to be damp-proofed or waterproofed with a liquid coating, basement waterproofing membrane (even under the concrete slab floor where polyethylene sheeting is commonly used), or an additive to the concrete.
Waterproofing	In construction	Within the waterproofing industry, below-ground waterproofing is generally divided into two areas: Tanking: This is waterproofing used where the below-ground structure will be sitting in the water table continuously or periodically. This causes hydrostatic pressure on both the membrane and structure and requires full encapsulation of the basement structure in a tanking membrane, under slab and walls.
Waterproofing	In construction	Damp proofing: This is waterproofing used where the water table is lower than the structure and there is good free-draining fill. The membrane deals with the shedding of water and the ingress of water vapor only, with no hydrostatic pressure. Generally, this incorporates a damp proof membrane (DPM) to the walls with a polythene DPM under the slab. With higher grade DPM, some protection from short-term Hydrostatic pressure can be gained by transitioning the higher quality wall DPM to the slab polythene under the footing, rather than at the footing face.In buildings using earth sheltering, too much humidity can be a potential problem, so waterproofing is critical. Water seepage can lead to mold growth, causing significant damage and air quality issues. Properly waterproofing foundation walls is required to prevent deterioration and seepage.
Waterproofing	In construction	Another specialized area of waterproofing is rooftop decks and balconies. Waterproofing systems have become quite sophisticated and are a very specialized area. Failed waterproof decks, whether made of polymer or tile, are one of the leading causes of water damage to building structures and personal injury when they fail. Where major problems occur in the construction industry is when improper products are used for the wrong application. While the term waterproof is used for many products, each of them has a very specific area of application, and when manufacturer specifications and installation procedures are not followed, the consequences can be severe. Another factor is the impact of expansion and contraction on waterproofing systems for decks. Decks constantly move with changes in temperatures, putting stress on the waterproofing systems. One of the leading causes of waterproof deck system failures is the movement of underlying substrates (plywood) that cause too much stress on the membranes resulting in a failure of the system. While beyond the scope of this reference document, waterproofing of decks and balconies is a complex of many complimentary elements. These include the waterproofing membrane used, adequate slope-drainage, proper flashing details, and proper construction materials.
Waterproofing	In construction	The penetrations through a building envelope must be built in a way such that water does not enter the building, such as using flashing and special fittings for pipes, vents, wires, etc. Some caulkings are durable, but many are unreliable for waterproofing. Also, many types of geomembranes are available to control water, gases, or pollution.
Waterproofing	In construction	From the late 1990s to the 2010s, the construction industry has had technological advances in waterproofing materials, including integral waterproofing systems and more advanced membrane materials. Integral systems such as hycrete work within the matrix of a concrete structure, giving the concrete itself a waterproof quality. There are two main types of integral waterproofing systems: the hydrophilic and the hydrophobic systems. A hydrophilic system typically uses a crystallization technology that replaces the water in the concrete with insoluble crystals. Various brands available in the market claim similar properties, but not all can react with a wide range of cement hydration by-products and thus require caution. Hydrophobic systems use concrete sealers or even fatty acids to block pores within the concrete, preventing water passage.
Waterproofing	In construction	Sometimes the same materials used to keep water out of buildings are used to keep water in, such as a pool or pond liners. New membrane materials seek to overcome shortcomings in older methods like polyvinyl chloride (PVC) and high-density polyethylene (HDPE). Generally, new technology in waterproof membranes relies on polymer-based materials that are very adhesive to create a seamless barrier around the outside of a structure. Waterproofing should not be confused with roofing, since roofing cannot necessarily withstand hydrostatic head while waterproofing can. The standards for waterproofing bathrooms in domestic construction have improved over the years, due in large part to the general tightening of building codes.
Waterproofing	In clothing	Some garments, and tents, are designed to give greater or lesser protection against rain. For urban use raincoats and jackets are used; for outdoor activities in rough weather there is a range of hiking apparel. Typical descriptions are "showerproof", "water resistant", and "waterproof". These terms are not precisely defined. A showerproof garment will usually be treated with a water-resisting coating, but is not rated to resist a specific hydrostatic head. This is suitable for protection against light rain, but after a short time water will penetrate. A water-resistant garment is similar, perhaps slightly more resistant to water but also not rated to resist a specific hydrostatic head. A garment described as waterproof will have a water-repellent coating, with the seams also taped to prevent water ingress there. Better waterproof garments have a membrane lining designed to keep water out but allow trapped moisture to escape ("breathability")—a totally waterproof garment would retain body sweat and become clammy. Waterproof garments specify their hydrostatic rating, ranging from 1,500 for light rain, to 20,000 for heavy rain.
Waterproofing	In clothing	Waterproof garments are intended for use in weather conditions which are often windy as well as wet and are usually also wind resistant. Footwear can also be made waterproof by using a variety of methods including but not limited to, the application of beeswax, waterproofing spray, or mink oil.
Waterproofing	In other objects	Waterproofing methods have been implemented in many types of objects, including paper packaging, cosmetics, and more recently, consumer electronics. Electronic devices used in military and severe commercial environments are routinely conformally coated in accordance with IPC-CC-830 to resist moisture and corrosion but encapsulation is needed to become truly waterproof. Even though it is possible to find waterproof wrapping or other types of protective cases for electronic devices, a new technology enabled the release of diverse waterproof smartphones and tablets in 2013. This method is based on a special nanotechnology coating a thousand times thinner than a human hair which protects electronic equipment from damage due to the penetration of water. Several manufacturers use the nano coating method on their smartphones, tablets, and digital cameras.
Waterproofing	In other objects	A 2013 study found that nanotextured surfaces using cone forms produce highly water-repellent surfaces. These nanocone textures are superhydrophobic (extremely water-hating).
Waterproofing	Applications	Waterproof packaging or other types of protective cases for electronic devices can be found. A new technology enabled the release of various waterproof smartphones and tablets in 2013. A study from 2013 found that nano-textured surfaces using cone shapes produce highly water-repellent surfaces. These "nanocone" textures are superhydrophobic.
Waterproofing	Standards	ASTM C1127 - Standard Guide for Use of High Solids Content, Cold Liquid-Applied Elastomeric Waterproofing Membrane with an Integral Wearing Surface ASTM D779 - Standard Test Method for Determining the Water Vapor Resistance of Sheet Materials in Contact with Liquid Water by the Dry Indicator Method ASTM D2099 - Standard Test Method for Dynamic Water Resistance of Shoe Upper Leather by the Maeser Water Penetration Tester ASTM D3393 - Standard Specification for Coated Fabrics Waterproofness D6135 - Standard Practice for Application of Self-Adhering Modified Bituminous Waterproofing ASTM D7281 - Standard Test Method for Determining Water Migration Resistance Through Roof Membranes British Standards Institution BS.8102:2009 - "Protection of Below Ground Structures against Water from the Ground".
Waterproofing	Standards	IEC 60529 - Degrees of protection provided by enclosures (IP Code) ISO 2281 - Horology — Water-resistant watches
Pin insulator	Pin insulator	A pin insulator is a device that isolates a wire from a physical support such as a pin (a wooden or metal dowel of about 3 cm diameter with screw threads) on a telegraph or utility pole. It is a formed, single layer shape that is made out of a non-conducting material, usually porcelain or glass. It is thought to be the earliest developed overhead insulator and is still popularly used in power networks up to 33 KV. Single or multiple pin insulators can be used on one physical support, however, the number of insulators used depends upon the application's voltage.Pin insulators are one of three types of overhead insulators, the others being strain insulators and suspension insulators. Unlike the others, pin insulators are directly connected to the physical support compared to being suspended from the wire. Pin insulators are shaped to allow the secure attachment of the conducting wire and avoid it coming adrift. The wire is usually attached to the insulator by being wrapped around it or in other circumstances, fixed into grooves on the insulator itself.When an insulator is wet, its outer surface becomes conductive making the insulator less effective. An insulator has an umbrella-like design so that it can protect the lower part of the insulator from rain. To keep the inner side of the insulator dry, ridges around the insulator, "rain sheds", are made. These increase the creepage distance from the energized wire to the mounting pin.
Pin insulator	Collecting	Pin insulators have become collectible items. All glass pin insulators are assigned a Consolidated Design (CD) number, a system first implemented by hobbyist N.R. Woodward in 1954, and widely introduced starting in 1965 by collector Helmer Turner. CD numbers first appeared in print in Woodward’s “Glass insulators in America, 1967 report”. Each CD number corresponds to a specific glass style, shape, or manufacturer. CD numbers are only hobby-specific for collectors, and are not used or recognised by insulator manufacturers.Insulators, at the time of manufacturing, were simply viewed as an engineering product and were not meant to be an entertainment product for spectators. This meant that the quality of the insulators was not a primary concern of the manufacturers that made them. The finished product was usually discoloured from impurities and foreign objects diffused within the molten glass and metal molds. These impurities give the insulator a unique character and high value as collectors would rather obtain an imperfect product rather than a perfect, common product. Impurities in the glass can create amber swirls, milk swirls, graphite inclusions, and two or three-tone insulators. Foreign objects contained within the glass are known to be nails, pennies, and screws.Although glass insulators are the most popular for the majority of collectors, many people collect porcelain insulators as well. These also come in a variety of shapes, sizes, and colors. They are classified in the U and M systems, primarily developed by Jack Tod and Elton Gish.
Pin insulator	Manufacturers	One of the major U.S. manufacturers that produced glass insulators during the 19th century and early 20th century in the USA was Brookfield Glass Company. It can be assumed that Brookfield may have had poor quality control as their insulators seem to be found with the most imperfections, however, this could be disputed.
Pin insulator	Manufacturers	Another major U.S. manufacturer that produced glass insulators was the Hemingray Glass Company. They were known for producing the most variety of colors. Some examples of colors that the company produced are yellow, golden yellow, butterscotch, glowing orange, amber, whiskey amber, "root beer" amber, orange-amber, red-amber, oxblood, green, lime green, sage green, depression green, emerald green, olive green, yellow-olive green, aqua, cornflower blue, electric blue, cobalt blue, sapphire blue, glowing peacock blue, and many others. Different colors were produced to allow two or more different utility companies to quickly identify which wires were theirs by the color of insulator if multiple wires were strung over the same utility pole. For example, one company may have a string of amber insulators, while another, on the same poles, might have their insulators in cobalt blue.
Pin insulator	Manufacturers	There are many manufacturers in the United States, Canada, and other countries that can be found embossed on all styles of insulators. A non-comprehensive list of these manufacturers is below: United States AT&T American Insulator Company Armstrong Brookfield Glass Company Beaver Falls Glass Company Baltimore glass manufacturing company Barclay Birmingham Boston bottle works Buzby California California Electric Works Chambers Chester Chicago Insulating Company Duquesne Electrical Construction and Maintenance Company Emminger’s Gayner Greeley Gregory Good Hawley Homer Brooks Hamilton Hemingray Glass Company King City Glass Works (K.C.G.W.) Kerr Knowles Kimble Luther G. Tillotson & Company Lefferts Locke Lynchburg McLaughlin Maydwell McKee & Co.
Pin insulator	Manufacturers	McMicking Mulford & Biddle New England Glass Manufacturing Company (N.E.G.M.Co.) National Insulator Company Oakman Manufacturing Company Ohio Valley Glass Company (O.V.G.Co.) Owens Illinois Paisley Pyrex Sterling Seiler’s Standard Glass Insulator Company Thomas-Houston Electric Company Thames Glass Works Twiggs Western Electric Manufacturing Company Western Glass Manufacturing Company Western Flint Glass Company Whitall Tatum Company Canada Diamond Dominion Hamilton Glass Works G.N.W.TEL. Co.
Pin insulator	Manufacturers	International Agee (Australia) Isorex (France) Miva (Italy) Telgraficos Nacionales (Mexico) Zicme (South America)
Nålebinding	Nålebinding	Nålebinding (Danish: literally 'binding with a needle' or 'needle-binding', also naalbinding, nålbinding, nålbindning or naalebinding) is a fabric creation technique predating both knitting and crochet. Also known in English as "knotless netting", "knotless knitting", or "single-needle knitting", the technique is distinct from crochet in that it involves passing the full length of the working thread through each loop, unlike crochet where the work is formed only of loops, never involving the free end. It also differs from knitting in that lengths must be pieced together during the process of nålebinding, rather than a continuous strand of yarn that can easily be pulled out. Archaeological specimens of fabric made by nålebinding can be difficult to distinguish from knitted fabric.
Nålebinding	Nålebinding	Nålebinding is still practiced by women of the Nanti tribe, an indigenous people of the Camisea region of Peru. They use it to make bracelets. Nålebinding also remains popular in the Scandinavian countries, as well as in the Balkans.
Nålebinding	History	The oldest known textile fragment of Nålbinding dating from c. 6500 BCE was found in Nahal Hemar Cave, Israel. Another made of lime bast fibre, from the Ertebølle period c. 4200 BCE was found in Tybrind Vig, a Mesolithic fishing village in Denmark.The oldest known samples of single-needle knitted clothing include the color-patterned sandal socks of the Coptic Christians of Egypt (4th century CE), and hats and shawls from the Paracas and Nazca cultures in Peru, dated between 300 BCE and 300 CE.Historically needles were made out of wood, antler, or bone. Contemporary selections also include plastic.
Nålebinding	History	Nålbinding predates knitting and crochet. Historical samples have often been misidentified as knitting due to how similar they can appear in the finished products if made using the Coptic stitch. Often a textile historian will need to closely follow the path of the yarn itself to identify the item as either knitting or nålbinding. This is possible by knowing the textile structures created by the two crafts and identifying those within the fabric or by looking for a frequent use of joining of strands.
Nålebinding	History	Nålbinding was used during the Viking age of 793–1066 CE in Scandinavia before knitting and crochet were known. This was an effective method for them to create sturdy, serviceable garments. Nålbinding requires working with several short pieces of yarn (each usually hardly more than 2 meters long), which are connected together by humidifying each extremity in order to bind them together through felting, thus creating the appearance of one continuous thread.
Nålebinding	History	The term "nålebinding" was introduced in the 1970s.A famous piece of nålbinding is the 'Coppergate sock' found during an excavation of the Coppergate area of York. A clear Viking influence in the textiles was found in the finds in this area. This was a wool sock that had been created using a technique never before recorded in England. The sock was slipper-like in style and would have covered the whole foot.
Nålebinding	History	Nålbinding was used in some regions of Northern Europe until the 1950s, when it most likely declined because of the changes in the textile industry and almost disappeared. It later gained renewed interest among many textile historians, archaeologists, craftspeople and reenactors, so that it is today an exotic but well-kept handicraft tradition.
Nålebinding	Technique	The method creates an elastic fabric using short lengths of yarn and a single-eyed needle that is often broad and flat. The stitches are commonly, but not invariably, gauged by wrapping them around the thumb. In its simplest form, the needle is passed through a seed loop to form a new loop, taking care to avoid tightening either into a firm knot. The needle is then passed through the new loop, repeating the process until a chain of desired length has been formed. Subsequent stitches are formed in the same manner but are also joined laterally to the corresponding stitch in the chain. The extended process is similarly repeated with reference to the preceding row rather than the initial chain. Fabric is commonly worked in a single direction – "in the round" – forming spirals and tubes for socks and mittens. The work may also be turned at the end of a row for fabric "worked flat".
Nålebinding	Technique	Crafters nowadays often use a specialised notation called the Hansen code to create patterns and communicate about the nålebinding technique. This code has been developed in 1990 by Egon Hansen, an expert on textile reconstruction who worked at the Moesgård Museum in Denmark.
Nålebinding	Technique	The Hansen code is a coding system used to indicate the path of the needle as it is worked through the preexisting fabric, with its passage under a loop shown as U and over a loop as O. A slash shows where the yarn changes direction and returns through loops it has already passed. If a loop is skipped an O or a U is put in brackets. If there is more than one change of direction a colon is used. The connection to the previous row is described using the letter F (if the yarn passes through the loop from the front) or B (if the yarn passes through the loop from the back), as well as a number to show how many loops are worked in this way. Stitches that can be described in this manner vary significantly in appearance, texture, and elasticity. As an example, the Coppergate sock described above was made in York stitch, or UU/OO O F2. As an example to show the use of brackets and colons, the Ålse stitch is U(U)O/UO:UO O. Some people prefer to use superscript numbers to describe the age of the passed loops, as it provides a clearer description for practical nalbinding than the brackets and colons.Wool yarn is often used because short lengths of it can easily be joined together, as the technique intrinsically requires. However, yarn made of fibers that do not felt as easily can be joined in other ways.In the construction of the 'Coppergate sock', the work began at the toe and worked in circular rows. Looping continued by the passing of the needle through two loops of the previous row, one of which had already been worked, and then brought back through the last two loops of the current row. A heavy, thick fabric was created with great elasticity. No loose ends were visible and are thought to be joined by splicing or having been stitched into the fabric. Shaping was achieved by adding an extra loop or leaving a lower loop out of the sequence. The heel had been turned back on itself several times to create the heel shaping.
Nålebinding	Characteristics	Nålebinding is often called more laborious and slower than knitting. This is not necessarily true, especially for the simpler stitches, such as the Oslo-, Mammen- and Brodén-stitches. Although each stitch might take slightly longer than a knitted one, nålbinding is often quicker than knitting, because each row's height (in the most common nålbinding-techniques) corresponds to 2–3 rows of knitting. It is also easier on the shoulders, back and hands, and the fabric it produces can be more dense and durable than knitted fabric. It is still used in Peru and Iran to make socks, and in parts of Scandinavia to make hats, gloves and other items that are very warm.[1]Another common mistake is to think of nålbinding as superior to knitting, because it requires more skill. It is very easy to learn and master; given proper instruction, even the more complex techniques are quite possible to learn with comparably little prior knowledge (though some is recommended). It can create different textiles, thin and flexible ones as well as thick and comparably stiff ones, depending on which technique is used. Nålbinding does not unravel and therefore special finishing borders are not necessary.
Linguistic diversity index	Linguistic diversity index	Linguistic diversity index (LDI) may refer to either Greenberg's (language) Diversity Index or the related Index of Linguistic Diversity (ILD) from Terralingua, which measures changes in the underlying LDI over time.Greenberg's Diversity Index (LDI) is the probability that two people selected from the population at random will have different mother tongues; it therefore ranges from 0 (everyone has the same mother tongue) to 1 (no two people have the same mother tongue). The ILD measures how the LDI has changed over time; a global ILD of 0.8 indicates a 20% loss of diversity since 1970, but ratios above 1 are possible, and have appeared in regional indexes.The computation of the diversity index is based on the population of each language as a proportion of the total population. The index cannot fully account for the vitality of languages. Also, the distinction between a language and a dialect is fluid and often political. A great number of languages are considered to be dialects of another language by some experts and separate languages by others. The index does not consider how different the languages are from each other, nor does it account for second language usage; it considers only the total number of distinct languages, and their relative frequency as mother tongues.
Involuntary memory	Involuntary memory	Involuntary memory, also known as involuntary explicit memory, involuntary conscious memory, involuntary aware memory, madeleine moment, mind pops and most commonly, involuntary autobiographical memory, is a sub-component of memory that occurs when cues encountered in everyday life evoke recollections of the past without conscious effort. Voluntary memory, its opposite, is characterized by a deliberate effort to recall the past.
Involuntary memory	Occurrences	There appear to be at least three different contexts within which involuntary memory arises, as described by J.H. Mace in his book Involuntary Memory. These include those that occur in everyday life, those that occur during the processes of voluntary and involuntary recall, and those that occur as part of a psychiatric syndrome.
Involuntary memory	Occurrences	Precious Fragments These include involuntary memories as they arise in everyday mental functioning, comprising the most common occurrences. They are characterized by their element of surprise, as they appear to come into conscious awareness spontaneously. They are the products of common every-day experiences such as eating a piece of cake, bringing to mind a past experience evoked by the taste. Research suggests that such experiences are especially strong and frequent in relation to one's sense of smell. The term "precious fragments" was coined by Marigold Linton, a pioneer in the study of autobiographical memory research. This is reflected, for example, in Proust's experience of remembering, upon dunking a madeleine cake in his tea in adulthood, a memory from childhood that occurred while eating madeleine dunked in tea.
Involuntary memory	Occurrences	By-products of other memories These are less common, and appear to be the result of voluntary/involuntary retrieval. Characteristic of such occurrences is the triggering effect this has, as one involuntary memory leads to another and so on. Again, Linton describes her own experiences with such memories as "coming unbidden sometimes when my mind is silent, but also as by-products of searches for other information." Mace terms these “involuntary memory chains,” stating that they are the product of spreading activation in the autobiographical memory system. These involuntary retrievals are experienced when activations are strong or relevant enough to current cognitive activity that they come into consciousness. According to Mace, this suggests that autobiographical memories are organized primarily conceptually (“experiential type concepts: people, places, locations, activities, etc.”), while temporal associations are not retained over time the same way.
Involuntary memory	Occurrences	Not so precious fragments Finally, some involuntary memories arise from traumatic experiences, and as such are fairly rare compared to other involuntary memories. Subjects describe them as salient, repetitive memories of traumatic events. The troubling nature of such memories makes these occurrences important to clinical researchers in their studies of psychiatric syndromes such as post-traumatic stress disorder. Some researchers have found that involuntary memories tend to have more emotional intensity and less centrality to life story than voluntary memories do. However, one study also shows that recurrent involuntary memories post-trauma can be explained with the general mechanisms of autobiographical memory, and tend to not come up in a fixed, unchangeable form. This suggests that psychologists may be able to develop ways to help individuals deal with traumatic involuntary memories.
Involuntary memory	Occurrences	Implications for Dementia Patients Further research on the automatic nature of involuntary retrieval suggests that they may not require working memory input. Thus, one report hypothesizes that dementia patients may still have available precious autobiographical memories that remain inaccessible until “suitable triggers release them,” prodding at the possibility for caregivers to be trained to reactivate these memories to elicit positive emotional effects and maintain patients’ life stories and sense of identity. Further empirical research is needed, but this insight starts a hopeful path into improving dementia care.
Involuntary memory	History	Hermann Ebbinghaus Born in Bremen, Germany in 1850, Hermann Ebbinghaus is recognized as the first to apply the principles of experimental psychology to studying memory. He is especially well known for his introduction and application of nonsense syllables in studying memory, study of which led him to discover the forgetting curve and the spacing effect, two of his most well-known contributions to the field. Ebbinghaus was also the first to attempt a description of involuntary memory, stating that, "often, even after years, mental states once present in consciousness return to it with apparent spontaneity and without any act of the will; that is, they are reproduced involuntarily." He goes on to explain that these mental states were once experienced, rendering, by definition, their future spontaneous appearance into consciousness the act of remembering, though we may not always be aware of where or how we experienced this information the first time. Ebbinghaus also made the key note that these involuntary reproductions are not random or accidental; instead, "they are brought about through the instrumentality of other immediately present mental images," under the laws of association. This reflects congruence with Mace's and Linton's theory of involuntary memories as by-products of other memories, as discussed above.
Involuntary memory	History	Marcel Proust—Proustian memory Marcel Proust was the first person to coin the term involuntary memory, in his novel À la recherche du temps perdu (In Search of Lost Time or Remembrance of Things Past). Proust did not have any psychological background, and worked primarily as a writer.
Involuntary memory	History	Proust viewed involuntary memory as containing the "essence of the past," claiming that it was lacking from voluntary memory. When the protagonist of Proust's novel eats a tea soaked madeleine, a long-forgotten childhood memory of eating tea soaked madeleine with his aunt is restored to him. From this memory, he then proceeds to recall the childhood home he was in, and even the town itself. This becomes a theme throughout In Search of Lost Time, with sensations reminding the narrator of previous experiences. Proust dubbed these "involuntary memories".
Involuntary memory	Current research	Chaining One idea that has recently become the subject of studies on involuntary memory is chaining. This is the concept that involuntary memories have the tendency to trigger other involuntary memories that are related. Typically, it is thought to be the contents of involuntary memories that are related to one another, thereby causing the chaining effect.
Involuntary memory	Current research	In a diary study done by J.H Mace, participants reported that frequently, when one involuntary memory arose, it would quickly trigger a series of other involuntary memories. This was recognized as the cueing source for involuntary memories.In the work by Bernstein, the diary method was also applied to the study of involuntary memory chaining. The main hypothesis was that chaining would also occur on autobiographical memory tasks. Participants were asked to report the presence of involuntary memories while performing an autobiographical memory task. Results showed that participants did experience involuntary memory recall when they were recalling the past deliberately (also known as voluntary memory). This implies that involuntary memory production occurs as a product of chaining from voluntary memory—the deliberate recall of the past.
Involuntary memory	Current research	Priming A common question in the study of involuntary memory is related to priming; what is it that activates such a memory? Various studies have been conducted in recent years to observe the conditions under which involuntary memories are primed.
Involuntary memory	Current research	Mace, in one of his recent studies, wanted to test the notion that basic cognitive activities, such as thinking about the past, may prime involuntary memories. To test this idea, Mace set up a diary method study in which participants recorded involuntary memories they experienced during a two-week period, in a diary. During this two-week period, participants also had to come into a laboratory at intervals, and were instructed to recall memories from certain life periods (e.g., high school, first five years of marriage). Following this, comparing their involuntary memories to a control condition found that a significant number of their involuntary memories related to the time period they were instructed to recall. Such findings suggest that involuntary memories may be primed by even the simplest of cognitive tasks—namely, reminiscing and recalling the past.
Involuntary memory	Neurological basis	Research studies regarding the neurological functions of involuntary memory have been few in number. Thus far, only two neuroimaging studies have been conducted comparing involuntary memories to voluntary memories using Positron Emission Tomography (PET).
Involuntary memory	Neurological basis	The first study found that while involuntary memory retrieval is mediated by the hippocampus, a structure of the brain known to be associated with successful episodic memory retrieval, involvement of the hippocampus was independent of whether or not remembering was intentional. The researchers believe this suggests that involuntary memories may reflect the “relative automaticity” of hippocampally-mediated retrieval. However, their research mainly focuses on identifying areas and functions involved in intentional retrieval. Activity in the medial/lateral parietal and right prefrontal cortex was insensitive to depth of encoding, but rather, varied depending on the intentionality of retrieval. These areas were increasingly engaged during intentional retrieval, suggesting that one function of this region may be to align remembering to aid with current behavioral goals. This is distinct from involuntary memory, where individuals do not consciously retrieve memories that will be most helpful to their current situation; however, it remains unclear if this process is unconsciously undertaken by the brain. When dealing with involuntary word recognition tasks, activity in areas such as the left inferior frontal gyrus, left superior temporal gyrus, left hippocampus, and right superior occipital cortex have all been implicated. Yet, areas and structures that are uniquely associated with involuntary memory remain unclear and more research is needed to understand the cognitive and neurological basis of this memory phenomenon.
Involuntary memory	Neurological basis	The second study found that the medial temporal lobe, the posterior cingulate gyrus, and the precuneus, are activated during retrieval success with or without executive control seen within the right dorsolateral prefrontal cortex. This implies that involuntary memories are successfully retrieved using the same system as voluntary memory when retrieving perceptual information. This is significant because it suggests that voluntary and involuntary retrieval are largely not mediated by separate cortical networks, which raises questions for future research of what distinguishes the two sub-components of memory, if not cognitive pathways and brain activation areas. Further, it might be explored whether these similarities in cognitive mechanism reflect shared properties and impacts of the recalled memories themselves, regardless of intentionality of retrieval. In this particular study, voluntary and involuntary recall were both associated with increased activations in the posterior cingulated gyrus, left precuneus, and right parahippocampal gyrus. In addition, right dorsolateral prefrontal cortex, and left precuneus were more active during voluntary recall, while left dorsolateral prefrontal cortex was more active during involuntary recall. It is suggested that the activation seen in left dorsolateral prefrontal cortex during involuntary memory recall reflects the attempt to prevent the recollected material from interfering with the semantic judgment task.
Involuntary memory	Effects of age	Development While age plays a role in memory capabilities, it has been found that general strategies used to encode (to remember) memories is more important. Those that are better at memorizing information are more likely to have more involuntary memories. In younger children (ages 10 and under), it has also been found that inducing involuntary memory during testing produced significantly better results than using voluntary memory. This can be accomplished by posing a vague, mildly related question or sentence prior to the actual test question. In older children (aged 14 and above), the opposite holds, with strictly voluntary memory leading to better test results.
Involuntary memory	Effects of age	Reminiscence bump The reminiscence bump is the phenomenon where in memories formed during adolescence and early adulthood are more commonly remembered than those throughout other periods in life. This is due to the formation of self-identity or the development of cognitive abilities across the lifespan. It has been found that this is true for both voluntary and involuntary memories. Age has been found to have a difference on the amount of memories recalled, but no age differences were found in the specificity of involuntary memories.
Involuntary memory	The role of emotion	Emotion intensity Emotion plays a strong role in relation to memory. It has been found that memories associated with stronger emotions (e.g.: being happy at your wedding) are more easily remembered and quickly recalled, as are those formed during moments of intense stress. The same holds true for involuntary memories, with happy involuntary memories occurring twice as often as unhappy or neutral involuntary memories.
Involuntary memory	In clinical disorders	Posttraumatic stress disorder Often people who have been the victims of some type of trauma describe vivid memories that intrude on their thoughts spontaneously and without warning. Such mental intrusions, if maintained over time compose the hallmark symptom of posttraumatic stress disorder (PTSD).The DSM-IV defines a trauma as an event in which someone experiences, or witnesses' severe injury to themselves or others or a threat to their integrity. The person must also have responded with fear, helplessness or horror at the time of the trauma. The main psychological consequences of this include re-experiencing the traumatic event (through both intrusive thoughts and images), avoidance of trauma-related stimuli, and increased arousal levels.
Involuntary memory	In clinical disorders	When it comes to involuntary memory, researchers are mainly interested in the concept of these trauma-related intrusions, which generally involved some form of re-experiencing the event, including a sensory component (e.g., imagery in any modality be it visual, auditory etc.). These intrusions, often termed "flashbacks", make the victim feel as though they are reliving the trauma, and cause high levels of emotional arousal, and the sense of an impending threat. Typically, they are parts of the traumatic event that were most salient at the time, known as "hotspots" and have the definitive feature that they cause high levels of emotional distress, and may be difficult to recall deliberately. Although this is a defining feature of PTSD, intrusive memories are also frequently encountered in anxiety-based disorders, psychotic disorders and even within the general population. Regardless of the context in which they are encountered, intrusions tend to have the same central feature; that the stored information is being recalled involuntarily. It is thought that intrusions arise when an individual encounters stimuli similar to the stimuli that were processed and stored during the trauma, thus triggering the memory into the conscious mind. A common example is one in which someone who has the victim of a car crash, upon hearing the screeching of tires experiences a flashback of their own collision, as if they are back at the original event.
Involuntary memory	In clinical disorders	Psychosis Stressful and traumatic events, which may manifest as involuntary memories called flashbacks, may trigger a wide range of anxiety-based and psychotic disorders. Social phobia, bipolar disorder, depression, and agoraphobia, are a few examples of disorders that have influences from flashbacks.
Involuntary memory	In clinical disorders	Psychosis is defined as a range of perceptual presentations, with the associated symptoms frequently referred to as either positive or negative. Positive symptoms are delusional, and may include hallucinations, while negative symptoms are characterized by a "lack" of functioning, which may include a lack of affect (emotional feeling) and loss of motivation. One study found that there was a high prevalence of trauma in patients with severe mental illness. However, only a small percentage had been diagnosed with PTSD when displaying PTSD-like symptoms. Therefore, the more complex symptoms of psychosis may prevent the clinical detection required when diagnosing PTSD. In addition, those who have been diagnosed with PTSD and have an identified form of trauma show positive symptoms of psychosis such as delusions and/or hallucinations. Finally, it has been suggested that individuals suffering from psychosis may be more vulnerable to intrusions.
Positional advantage	Positional advantage	Positional advantage is a combative position relative to an opponent. It is used extensively to describe a situation of significant tactical advantage over an opponent in open-hand conflict (i.e. without weapons) in William Cheung's Traditional Wing Chun Kung Fu and Ian Protheroe's Classical Wing Chun.In physical altercations, positional advantage is significant because a defender who has attained positional advantage: is not as open to an attack from the attacker's rear hand may control the attacker's lead limbs (one arm and one leg) is in range to attack or defend both hands is able to redirect their opponent's forceIn the words of Sifu Ian Protheroe, "as long as your strongest side is facing your opponent's weakest side, you have the advantage". Although positional advantage has been adopted specifically by Classical and Traditional Wing Chun practitioners, the term is applicable to all martial styles, both with and without weapons. Related concepts include centre and central line theory. These terms are used to describe many different things by Wing Chun practitioners (see the Wikipedia entry for Wing Chun for more information).
Exceptional object	Exceptional object	Many branches of mathematics study objects of a given type and prove a classification theorem. A common theme is that the classification results in a number of series of objects and a finite number of exceptions — often with desirable properties — that do not fit into any series. These are known as exceptional objects. In many cases, these exceptional objects play a further and important role in the subject. Furthermore, the exceptional objects in one branch of mathematics often relate to the exceptional objects in others.A related phenomenon is exceptional isomorphism, when two series are in general different, but agree for some small values. For example, spin groups in low dimensions are isomorphic to other classical Lie groups.
Exceptional object	Regular polytopes	The prototypical examples of exceptional objects arise in the classification of regular polytopes: in two dimensions, there is a series of regular n-gons for n ≥ 3. In every dimension above 2, one can find analogues of the cube, tetrahedron and octahedron. In three dimensions, one finds two more regular polyhedra — the dodecahedron (12-hedron) and the icosahedron (20-hedron) — making five Platonic solids. In four dimensions, a total of six regular polytopes exist, including the 120-cell, the 600-cell and the 24-cell. There are no other regular polytopes, as the only regular polytopes in higher dimensions are of the hypercube, simplex, orthoplex series. In all dimensions combined, there are therefore three series and five exceptional polytopes.Moreover, the pattern is similar if non-convex polytopes are included: in two dimensions, there is a regular star polygon for every rational number p/q>2 . In three dimensions, there are four Kepler–Poinsot polyhedra, and in four dimensions, ten Schläfli–Hess polychora; in higher dimensions, there are no non-convex regular figures.
Exceptional object	Regular polytopes	These can be generalized to tessellations of other spaces, especially uniform tessellations, notably tilings of Euclidean space (honeycombs), which have exceptional objects, and tilings of hyperbolic space. There are various exceptional objects in dimension below 6, but in dimension 6 and above, the only regular polyhedra/tilings/hyperbolic tilings are the simplex, hypercube, cross-polytope, and hypercube lattice.
Exceptional object	Regular polytopes	Schwarz triangles Related to tilings and the regular polyhedra, there are exceptional Schwarz triangles (triangles that tile the sphere, or more generally Euclidean plane or hyperbolic plane via their triangle group of reflections in their edges), particularly the Möbius triangles. In the sphere, there are 3 Möbius triangles (and 1 1-parameter family), corresponding to the 3 exceptional Platonic solid groups, while in the Euclidean plane, there are 3 Möbius triangles, corresponding to the 3 special triangles: 60-60-60 (equilateral), 45-45-90 (isosceles right), and 30-60-90. There are additional exceptional Schwarz triangles in the sphere and Euclidean plane. By contrast, in the hyperbolic plane, there is a 3-parameter family of Möbius triangles, and none exceptional.
Exceptional object	Finite simple groups	The finite simple groups have been classified into a number of series as well as 26 sporadic groups. Of these, 20 are subgroups or subquotients of the monster group, referred to as the "Happy Family", while 6 are not, and are referred to as "pariahs". Several of the sporadic groups are related to the Leech lattice, most notably the Conway group Co1, which is the automorphism group of the Leech lattice, quotiented out by its center.
Exceptional object	Division algebras	There are only three finite-dimensional associative division algebras over the reals — the real numbers, the complex numbers and the quaternions. The only non-associative division algebra is the algebra of octonions. The octonions are connected to a wide variety of exceptional objects. For example, the exceptional formally real Jordan algebra is the Albert algebra of 3 by 3 self-adjoint matrices over the octonions.
Exceptional object	Simple Lie groups	The simple Lie groups form a number of series (classical Lie groups) labelled A, B, C and D. In addition, there are the exceptional groups G2 (the automorphism group of the octonions), F4, E6, E7, E8. These last four groups can be viewed as the symmetry groups of projective planes over O, C⊗O, H⊗O and O⊗O, respectively, where O is the octonions and the tensor products are over the reals.
Exceptional object	Simple Lie groups	The classification of Lie groups corresponds to the classification of root systems, and thus the exceptional Lie groups correspond to exceptional root systems and exceptional Dynkin diagrams.
Exceptional object	Supersymmetric algebras	There are a few exceptional objects with supersymmetry. The classification of superalgebras by Kac and Tierry-Mieg indicates that the Lie superalgebras G(3) in 31 dimensions and F(4) in 40 dimensions, and the Jordan superalgebras K3 and K10, are examples of exceptional objects.
Exceptional object	Unimodular lattices	Up to isometry, there is only one even unimodular lattice in 15 dimensions or less — the E8 lattice. Up to dimension 24, there is only one even unimodular lattice without roots, the Leech lattice. Three of the sporadic simple groups were discovered by Conway while investigating the automorphism group of the Leech lattice. For example, Co1 is the automorphism group itself modulo ±1. The groups Co2 and Co3, as well as a number of other sporadic groups, arise as stabilisers of various subsets of the Leech lattice.
Exceptional object	Codes	Some codes also stand out as exceptional objects, in particular the perfect binary Golay code, which is closely related to the Leech lattice. The Mathieu group 24 , one of the sporadic simple groups, is the group of automorphisms of the extended binary Golay code, and four more of the sporadic simple groups arise as various types of stabilizer subgroup of 24
Exceptional object	Block designs	An exceptional block design is the Steiner system S(5,8,24) whose automorphism group is the sporadic simple Mathieu group 24 The codewords of the extended binary Golay code have a length of 24 bits and have weights 0, 8, 12, 16, or 24. This code can correct up to three errors. So every 24-bit word with weight 5 can be corrected to a codeword with weight 8. The bits of a 24-bit word can be thought of as specifying the possible subsets of a 24 element set. So the extended binary Golay code gives a unique 8 element subset for each 5 element subset. In fact, it defines S(5,8,24).
Exceptional object	Outer automorphisms	Certain families of groups often have a certain outer automorphism group, but in particular cases, they have other exceptional outer automorphisms.
Exceptional object	Outer automorphisms	Among families of finite simple groups, the only example is in the automorphisms of the symmetric and alternating groups: for n≥3,n≠6 the alternating group An has one outer automorphism (corresponding to conjugation by an odd element of Sn ) and the symmetric group Sn has no outer automorphisms. However, for n=6, there is an exceptional outer automorphism of S6 (of order 2), and correspondingly, the outer automorphism group of A6 is not C2 (the group of order 2), but rather C2×C2 , the Klein four-group.If one instead considers A6 as the (isomorphic) projective special linear group PSL ⁡(2,9) , then the outer automorphism is not exceptional; thus the exceptional-ness can be seen as due to the exceptional isomorphism PSL ⁡(2,9).
Exceptional object	Outer automorphisms	This exceptional outer automorphism is realized inside of the Mathieu group 12 and similarly, 12 acts on a set of 12 elements in 2 different ways. Among Lie groups, the spin group Spin ⁡(8) has an exceptionally large outer automorphism group (namely S3 ), which corresponds to the exceptional symmetries of the Dynkin diagram D4 . This phenomenon is referred to as triality. The exceptional symmetry of the D4 diagram also gives rise to the Steinberg groups.
Exceptional object	Algebraic topology	The Kervaire invariant is an invariant of a (4k + 2)-dimensional manifold that measures whether the manifold could be surgically converted into a sphere. This invariant evaluates to 0 if the manifold can be converted to a sphere, and 1 otherwise. More specifically, the Kervaire invariant applies to a framed manifold, that is, to a manifold equipped with an embedding into Euclidean space and a trivialization of the normal bundle. The Kervaire invariant problem is the problem of determining in which dimensions the Kervaire invariant can be nonzero. For differentiable manifolds, this can happen in dimensions 2, 6, 14, 30, 62, and possibly 126, and in no other dimensions. The final case of dimension 126 remains open. These five or six framed cobordism classes of manifolds having Kervaire invariant 1 are exceptional objects related to exotic spheres. The first three cases are related to the complex numbers, quaternions and octonions respectively: a manifold of Kervaire invariant 1 can be constructed as the product of two spheres, with its exotic framing determined by the normed division algebra.Due to similarities of dimensions, it is conjectured that the remaining cases (dimensions 30, 62 and 126) are related to the Rosenfeld projective planes, which are defined over algebras constructed from the octonions. Specifically, it has been conjectured that there is a construction that takes these projective planes and produces a manifold with nonzero Kervaire invariant in two dimensions lower, but this remains unconfirmed.
Exceptional object	Symmetric quantum measurements	In quantum information theory, there exist structures known as SIC-POVMs or SICs, which correspond to maximal sets of complex equiangular lines. Some of the known SICs—those in vector spaces of 2 and 3 dimensions, as well as certain solutions in 8 dimensions—are considered exceptional objects and called "sporadic SICs". They differ from the other known SICs in ways that involve their symmetry groups, the Galois theory of the numerical values of their vector components, and so forth. The sporadic SICs in dimension 8 are related to the integral octonions.
Exceptional object	Connections	Numerous connections have been observed between some, though not all, of these exceptional objects. Most common are objects related to 8 and 24 dimensions, noting that 24 = 8 · 3. By contrast, the pariah groups stand apart, as the name suggests. 8 and 24 dimensions Exceptional objects related to the number 8 include the following. The octonions are 8-dimensional. The E8 lattice can be realized as the integral octonions (up to a scale factor). The exceptional Lie groups can be seen as symmetries of the octonions and structures derived from the octonions; further, the E8 algebra is related to the E8 lattice, as the notation implies (the lattice is generated by the root system of the algebra). Triality occurs for Spin(8), which also connects to 8 · 3 = 24.Likewise, exceptional objects related to the number 24 include the following. The Leech lattice is 24-dimensional. Most sporadic simple groups can be related to the Leech lattice, or more broadly the Monster.
Exceptional object	Connections	The exceptional Jordan algebra has a representation in terms of 24×24 real matrices together with the Jordan product rule.These objects are connected to various other phenomena in math which may be considered surprising but not themselves "exceptional". For example, in algebraic topology, 8-fold real Bott periodicity can be seen as coming from the octonions. In the theory of modular forms, the 24-dimensional nature of the Leech lattice underlies the presence of 24 in the formulas for the Dedekind eta function and the modular discriminant, which connection is deepened by Monstrous moonshine, a development that related modular functions to the Monster group.
Exceptional object	Connections	Physics In string theory and superstring theory we often find that particular dimensions are singled out as a result of exceptional algebraic phenomena. For example, bosonic string theory requires a spacetime of dimension 26 which is directly related to the presence of 24 in the Dedekind eta function. Similarly, the possible dimensions of supergravity are related to the dimensions of the division algebras.
Exceptional object	Connections	Monstrous moonshine Many of the exceptional objects in mathematics and physics have been found to be connected to each other. Developments such as the Monstrous moonshine conjectures show how, for example, the Monster group is connected to string theory. The theory of modular forms shows how the algebra E8 is connected to the Monster group. (In fact, well before the proof of the Monstrous moonshine conjecture, the elliptic j-function was discovered to encode the representations of E8.) Other interesting connections include how the Leech lattice is connected via the Golay code to the adjacency matrix of the dodecahedron (another exceptional object). Below is a mind map showing how some of the exceptional objects in mathematics and mathematical physics are related.
Exceptional object	Connections	The connections can partly be explained by thinking of the algebras as a tower of lattice vertex operator algebras. It just so happens that the vertex algebras at the bottom are so simple that they are isomorphic to familiar non-vertex algebras. Thus the connections can be seen simply as the consequence of some lattices being sub-lattices of others. Supersymmetries The Jordan superalgebras are a parallel set of exceptional objects with supersymmetry. These are the Lie superalgebras which are related to Lorentzian lattices. This subject is less explored, and the connections between the objects are less well established. There are new conjectures parallel to the Monstrous moonshine conjectures for these super-objects, involving different sporadic groups.
Exceptional object	Unexceptional objects	Pathologies "Exceptional" object is reserved for objects that are unusual, meaning rare, the exception, not for unexpected or non-standard objects. These unexpected-but-typical (or common) phenomena are generally referred to as pathological, such as nowhere differentiable functions, or "exotic", as in exotic spheres — there are exotic spheres in arbitrarily high dimension (not only a finite set of exceptions), and in many dimensions most (differential structures on) spheres are exotic.
Exceptional object	Unexceptional objects	Extremal objects Exceptional objects must be distinguished from extremal objects: those that fall in a family and are the most extreme example by some measure are of interest, but not unusual in the way exceptional objects are. For example, the golden ratio φ has the simplest continued fraction approximation, and accordingly is most difficult to approximate by rationals; however, it is but one of infinitely many such quadratic numbers (continued fractions).
Exceptional object	Unexceptional objects	Similarly, the (2,3,7) Schwarz triangle is the smallest hyperbolic Schwarz triangle, and the associated (2,3,7) triangle group is of particular interest, being the universal Hurwitz group, and thus being associated with the Hurwitz curves, the maximally symmetric algebraic curves. However, it falls in a family of such triangles ((2,4,7), (2,3,8), (3,3,7), etc.), and while the smallest, is not exceptional or unlike the others.
LigD	LigD	LigD is a multifunctional ligase/polymerase/nuclease (3'-phosphoesterase) found in bacterial non-homologous end joining (NHEJ) DNA repair systems. It is much more error-prone than the more complex eukaryotic system of NHEJ, which uses multiple enzymes to fill its role. The polymerase preferentially use rNTPs (RNA nucleotides), possibly advantageous in dormant cells.The actual architecture of LigD is variable. The LigD homolog in Bacillus subtilis does not have the nuclease domain. LigD with its ligase domain artificially removed can perform its function (with loss of fidelity) with a separate LigC acting as the ligase. The LigD homolog in the archaeon Methanocella paludicola is broken into three single-domain proteins sharing an operon.
Concrete cover	Concrete cover	Concrete cover, in reinforced concrete, is the least distance between the surface of embedded reinforcement and the outer surface of the concrete (ACI 130). The concrete cover depth can be measured with a cover meter. The purpose of concrete cover is to protect the reinforcement from corrosion, fire, and other potential damage. The required concrete cover depends on several factors, including the environmental conditions to which the structure will be exposed, the size of the reinforcing steel, the concrete strength, and the type of structure being constructed. Generally, larger diameter reinforcement bars require more concrete cover than smaller ones. In most cases, local building codes and engineering standards specify the minimum required concrete cover for various types of structures. It is important to adhere to these requirements to ensure the safety and longevity of the structure.
Concrete cover	Purpose of provision of concrete cover	The concrete cover must have a minimum thickness for three main reasons: to protect the steel reinforcement bars (rebars) from environmental effects to prevent their corrosion; to provide thermal insulation, which protects the reinforcement bars from fire, and; to give reinforcing bars sufficient embedding to enable them to be stressed without slipping.The premature failure of corroded steel reinforcements and the expansion of the iron corrosion products around the rebars are amongst the main causes of the concrete degradation. The carbon steel of rebars is protected from oxidation by atmospheric oxygen by the high pH of concrete interstitial water. Iron bar surface is passivated as long as the pH value is higher than 10.5. Fresh cement water has a pH of about 13.5 while evolved cement water pH ~ 12.5 is controlled by the dissolution of calcium hydroxide (portlandite). Carbon dioxide present in the air slowly diffuses through the concrete cover over the rebar and progressively reacts with the alkaline hydroxides (KOH, NaOH) and with calcium hydroxide leading to the carbonatation of the hydrated cement paste. As a result, the pH of the cement drops and when its value is below 10.5 – 9.5, steel surface is no longer passivated and starts to corrode. A sufficient thickness of concrete cover is thus required in order to slow down the carbonatation process towards the rebar. The minimum concrete cover will depend on the environmental conditions encountered and must be thicker when the concrete is also exposed to moisture and chloride (proximity to the sea, use of de-icing salt for bridges or roads, ...). A high quality concrete made with a low water-to-cement (w/c) ratio will have a lower porosity and will be less permeable to water and to the ingress of corrosive species (dissolved oxygen, chloride, ...). A thicker cover or a more compact concrete will also reduce the diffusion of CO2 in the concrete, protecting it better from carbonatation and maintaining a higher pH for a longer time period, increasing so the rebar service life.
Concrete cover	Structural applications	Concrete covers are frequently used in the construction of commercial developments, homes, bridges, municipalities, curb forming, and other locations or projects requiring long-lasting, durability. Concrete and steel reinforcement bars combine to create strong, resilient structures in the following ways: Upon contact with each other, the cement paste and steel rebar form a non-reactive surface film preventing corrosion. Reinforcement bars or beams can be strategically set throughout the concrete to achieve the required support system. The bond created by utilizing rebar and concrete can also be attributed to the ridged rebar surface. This allows stresses to transfer from the concrete to the steel, and from the steel to concrete. Concrete and steel have similar thermal expansion coefficients. Upon freezing or heating, they contract and expand in a similar manner, maintaining the structure needed.
Concrete cover	Guidelines	National codes also specify minimum cover requirements based on their respective local exposure conditions.
Concrete cover	Paradox	Large cover depths (50–75 mm) are required to protect reinforcement against corrosion in aggressive environments, but thick cover leads to increased crack widths in flexural reinforced concrete members. Large crack-widths (greater than 0.3 mm) permit ingress of moisture and chemical attack to the concrete, resulting in possible corrosion of reinforcement and deterioration of concrete. Therefore, thick covers defeat the very purpose for which it is provided. There is a need for judicious balance of cover depth and crack width requirements.
Concrete cover	Paradox	A possible economical solution for this paradox is the placing of a second layer of corrosion-resistant reinforcement like stainless steel rebars or meshes or FRP rebars in the concrete cover to distribute the cracks.

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