ratio of word probabilities predicted from brain for apartment and knife

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apartment

knife

top 10 words in brain distribution (in article):
build house state Unite public people service park building world top 10 words in brain distribution (in article):
iron blade steel handle cut metal tool nail hammer hand

top 10 words in brain distribution (not in article):
city store street town home bus road village department country top 10 words in brain distribution (not in article):
head hair size whip breast design cell sword century bra

times more probable under apartment 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under knife
(words not in the model)

An apartment'" is a self-contained housing unit that occupies only part of a building. Apartments may be owned (by an "owner occupier") or rented (by "tenants"). A common alternative term for apartment is flat'". The term "apartment" is favored in North America, whereas the term "flat" is commonly, but not exclusively, used in the United Kingdom, Ireland and the Commonwealth nations. In Malaysian English, "flat" often denotes a housing block of lesser quality meant for lower-income groups, while "apartment" is more generic and may also include luxury condominiums. In the US, some apartment-dwellers own their own apartments, either as co-ops, in which the residents own shares of a corporation that owns the building or development; or in condominiums, whose residents own their apartments and share ownership of the public spaces. Most apartments are in buildings designed for the purpose, but large older houses are sometimes divided into apartments. The word "apartment" connotes a residential unit or section in a building. In some locations, particularly the United States, the word denotes a rental unit owned by the building owner, and is not typically used for a condominium. In the UK, some flat owners own a share in the company that owns the freehold of the building. This is commonly known as a "share of freehold" flat. The freehold company has the right to collect annual ground rents from each of the flat owners in the building. The freeholder can also develop or sell the building, subject to the usual planning and restrictions that might apply. The word unit'" is a more general term referring to both apartments and rental business suites. The word is generally used only in the context of a specific building. E.g., "This building has three units" or "I'm going to rent a unit in this building", but not "I'm going to rent a unit somewhere." When there is no tenant occupying an apartment, the apartment owner or landlord is said to have a "vacancy". For apartment landlords, each vacancy represents a loss of income from rent-paying tenants for the time the apartment is vacant (i.e., unoccupied). Landlords' objectives are often to minimize the vacancy rate for their units. The owner of the apartment, typically when transferring possession to the occupant, gives him her the key to the apartment entrance and any other keys needed, such as a common key to the building or any other common areas and a mailbox key. When the occupant(s) move out, these keys are typically returned to the owner. Apartment types and characteristics. Apartments can be classified into several types. In the US the typical terms are a Studio'", "'efficiency'", bedsit, or bachelor style apartment. These all tend to be the smallest apartments with the cheapest rents in a given area. These kinds of apartment usually consist mainly of a large room which is the living, dining, and bedroom combined. There are usually kitchen facilities as part of this central room, but the bathroom is its own smaller separate room. Moving up from the efficiencies are "'one-bedroom apartments'", in which one bedroom is separate from the rest of the apartment. Then there are "'two-bedroom'", "'three-bedroom'", etc. apartments. Small apartments often have only one entrance. Large apartments often have two entrances, perhaps a door in the front and another in the back. Depending on the building design, the entrance doors may be directly to the outside or to a common area inside, such as a hallway. Depending on location, apartments may be available for rent "'furnished'" with furniture or "'unfurnished'" into which a tenant usually moves in with their own furniture. A "'garden apartment'" has some characteristics of a townhouse: each apartment has its own entrance, and apartments are not placed vertically over one another. However, a garden apartment is usually only one story high and never more than two stories; they are often one-bedrooms and almost never more than two-bedrooms. Some garden apartment buildings place a one-car garage under each apartment, with pedestrian entrances from a common courtyard open at one end. The grounds are more landscaped than for other modestly scaled apartments. (Alternately, "garden apartment" can refer to a unit built half below grade, putting its windows at garden level. Laundry facilities may be found in a common area accessible to all the tenants in the building, or each apartment may have its own facilities. Depending on when the building was built and the design of the building, utilities such as water, heating, and electricity may be common for all the apartments in the building or separate for each apartment and billed separately to each tenant (however, many areas in the US have ruled it illegal to split a water bill among all the tenants, especially if a pool is on the premises). Outlets for connection to telephones are typically included in apartments. Telephone service is optional and is practically always billed separately from the rent payments. Cable television and similar amenities are extra also. Parking space(s), air conditioner, and extra storage space may or may not be included with an apartment. Rental leases often limit the maximum number of people who can reside in each apartment. On or around the ground floor of the apartment building, a series of mailboxes are typically kept in a location accessible to the public and, thus, to the mailman too. Every unit typically gets its own mailbox with individual keys to it. Some very large apartment buildings with a full-time staff may take mail from the mailman and provide mail-sorting service. Near the mailboxes or some other location accessible by outsiders, there may be a buzzer (equivalent to a doorbell) for each individual unit. In smaller apartment buildings such as two- or three-flats, or even four-flats, garbage is often disposed of in trash containers similar to those used at houses. In larger buildings, garbage is often collected in a common trash bin or Dumpster. For cleanliness or minimizing noise, many lessors will place restrictions on tenants regarding keeping pets in an apartment. In some parts of the world, the word apartment refers to a new purpose-built self-contained residential unit in a building, whereas the word "flat" means a converted self-contained unit in an older building. An industrial, warehouse, or commercial space converted to an apartment is commonly called a loft. When part of a house is converted for the ostensible use of a landlord's family member, the unit may be known as an "in-law" apartment or "granny flat", though these (sometimes illegally) created units are often occupied by ordinary renters rather than family members. In Canada these suites are commonly located in the basements of houses and are therefore normally called "basement suites" or "mother-in-law suites." In Milwaukee vernacular architecture, a Polish flat is an existing small house or cottage that has been lifted up to accommodate the creation of a new basement floor housing a separate apartment, then set down again; thus becoming a modest two-story flat. In Russia, a communal apartment'" («коммуналка») is a room with a shared kitchen and bath. A typical arrangement is a cluster of five or so apartments with their common kitchen and bathroom and their own front door, occupying a floor in a pre-Revolutionary mansions. Traditionally a room is owned by the government and assigned to a family on a semi-permanent basis. It is possible to "privatize" a room by paying a large sum of money to the government; then it can legally be sold. A knife'" is a handheld sharp-edged instrument consisting of a handle attached to a blade that is used for cutting. Knives were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools. History. The earliest knives were shaped by knapping (percussive flaking) of rock, particularly harder rocks such as obsidian and flint. During the Paleolithic era Homo habilis likely made similar tools out of wood, bone, and similar perishable materials that have not survived. As recent as five thousand years ago, as advances in metallurgy progressed, stone, wood, and bone blades were gradually succeeded by copper, bronze, iron, and eventually steel. The first metal (copper) knives were symmetrical double edged daggers, which copied the earlier flint daggers. In Europe the first single edged knives appeared during the middle bronze age. Modern knives may be made from many different materials such as alloy tool steels, carbon fiber, ceramics, and titanium. Materials and construction. Today, knives come in many forms but can be generally categorized between two broad types: fixed blade knives and folding, or pocket, knives. Modern knives consist of a "blade" (1'") and "handle" (2'"). The blade edge can be plain or serrated or a combination of both. The handle, used to grip and manipulate the blade safely, may include the "tang", a portion of the blade that extends into the handle. Knives are made with partial (extending part way into the handle) and full (extending the full length of the handle, often visible on top and bottom) tangs. The handle can also include a bolster, which is a piece of material used to balance the knife, usually brass or other metal, at the front of the handle where it meets the blade. The blade consists of the "point" (3'"), the end of the knife used for piercing, the "edge" (4'"), the cutting surface of the knife extending from the point to the heel, the "grind" (5'"), the "cross-section" shape of the blade, the "spine", (6'"), the top, thicker portion of the blade, the "fuller" (7'"), the groove added to lighten the blade, and the "ricasso" (8'"), the thick portion of the blade joining the blade and the handle. The "guard" (9'") is a barrier between the blade and the handle which protects the hand from an opponent, or the blade of the knife itself. A "choil", where the blade is unsharpened and possibly indented as it meets the handle, may be used to prevent scratches to the handle when sharpening or as a forward-finger grip. The end of the handle, or "butt" (10'"), may allow a "lanyard" (11'"), used to secure the knife to the wrist, or a portion of the tang to protrude as a striking surface for pounding or glass breaking. Blade. Knife blades can be manufactured from a variety of materials, each of which has advantages and disadvantages. Carbon steel, an alloy of iron and carbon, can be very sharp, hold its edge well, and remain easy to sharpen, but is vulnerable to rust and stains. Stainless steel is an alloy of iron, chromium, possibly nickel, and molybdenum, with only a small amount of carbon. It is not able to take quite as sharp an edge as carbon steel, but is highly resistant to corrosion. High carbon stainless steel is stainless steel with a higher amount of carbon, intended to incorporate the better attributes of carbon steel and stainless steel. High carbon stainless steel blades do not discolor or stain, and maintain a sharp edge. Laminate blades use multiple metals to create a layered sandwich, combining the attributes of both. For example, a harder, more brittle steel may be sandwiched between an outer layer of softer, tougher, stainless steel to reduce vulnerability to corrosion. In this case, however, the part most affected by corrosion, the edge, is still vulnerable. Pattern-welding is similar to laminate construction. Layers of different steel types are welded together, but then the stock is manipulated to create patterns in the steel. Titanium is metal that has a better strength-to-weight ratio, is more wear resistant, and more flexible than steel. Although less hard and unable to take as sharp an edge, carbides in the titanium alloy allow them to be heat-treated to a sufficient hardness. Ceramic blades are hard, brittle, and lightweight: they may maintain a sharp edge for years with no maintenance at all. They are immune to common corrosion, and can only be sharpened on silicon carbide sandpaper and some grinding wheels. Plastic blades are not especially sharp and typically serrated. They are often disposable. Steel blades are commonly shaped by forging or stock removal. Forged blades are made by heating a single piece of steel, then shaping the metal while hot using a hammer or press. Stock removal blades are shaped by grinding and removing metal. With both methods, after shaping, the steel must be heat treated. This involves heating the steel above its critical point, then quenching the blade to harden it. After hardening, the blade is tempered to remove stresses and make the blade tougher. Mass manufactured kitchen cutlery uses both the forging and stock removal processes. Forging tends to be reserved for manufacturers' more expensive product lines, and can often be distinguished from stock removal product lines by the presence of an integral bolster, though integral bolsters can be crafted through either shaping method. Knives are sharpened in various ways. Flat ground blades have a profile that tapers from the thick spine to the sharp edge in a straight or convex line. Seen in cross section, the blade would form a long, thin triangle, or where the taper does not extend to the back of the blade, a long thin rectangle with one peaked side. Hollow ground blades have concave, beveled edges. The resulting blade has a thinner edge, so it may have better cutting ability for shallow cuts, but it is lighter and less durable than flat ground blades and will tend to bind in deep cuts. Serrated blade knives have a wavy, scalloped or saw-like blade. Serrated blades are more well suited for tasks that require aggressive 'sawing' motions, whereas plain edge blades are better suited for tasks that require push-through cuts (e.g., shaving, chopping). Fixed blade features. A fixed blade knife does not fold or slide, and is typically stronger due to the tang, the extension of the blade into the handle, and lack of moving parts. Folding blade features. A folding knife connects the blade to the handle through a pivot, allowing the blade to fold into the handle. To prevent injury to the knife user through the blade accidentally closing on the user's hand, folding knives typically have a locking mechanism. Different locking mechanisms are favored by various individuals for reasons such as perceived strength (lock safety), legality, and ease of use. Another prominent feature on many folding knives is the opening mechanism. Traditional pocket knives and Swiss Army Knives commonly employ the nail nick, while modern folding knives more often use a stud, hole, disk, or "flipper" located on the blade, all which have the benefit of allowing the user to open the knife with one hand. "Automatic" or "switchblade" knives open using the stored energy from a spring that is released when the user presses a button or lever or other actuator built into the handle of the knife. Automatic knives are popular amongst law enforcement and military users for their ease of rapid deployment and their ability to be opened using only one hand. Automatic knives are severely restricted by law in most states. Increasingly common are "assisted opening" knives which use springs to propel the blade once the user has moved it past a certain angle. These differ from automatic or switchblade knives in that the blade is not released by means of a button or catch on the handle; rather, the blade itself is the actuator. Most assisted openers use flippers as their opening mechanism. Assisted opening knives can be as fast or faster than automatic knives to deploy. Sliding blade features. A sliding knife is a knife which can be opened by sliding the knife blade out the front of the handle. One method of opening is where the blade exits out the front of the handle point-first and then is locked into place (an example of the this is the gravity knife). Another form is a O-T-F (out-the-front) switchblade, which only requires the push of a button or spring to cause the blade to slide out of the handle, and lock into place. To retract the blade back into the handle, a release lever or button, usually the same control as to open, is pressed. A very common form of sliding knife is the sliding utility knife (commonly known as a stanley knife). Handle. The handles of knives can be made from a number of different materials, each of which has advantages and disadvantages. Handles are produced in a wide variety of shapes and styles. Handles are often textured to enhance grip. More exotic materials usually only seen on art or ceremonial knives include: Stone, bone, mammoth tooth, mammoth ivory, oosic (walrus penis bone), walrus tusk, antler (often called stag in a knife context), sheep horn, buffalo horn, teeth, etc. Many materials have been employed in knife handles. Knives as weapons. As a weapon, the knife is universally adopted as an essential tool. For example: Knives as utensils. A primary aspect of the knife as a tool includes dining, used either in food preparation or as cutlery. Examples of this include: Knives as tools. As a utility tool the knife can take many forms, including: Rituals and superstitions. The knife plays a significant role in some cultures through ritual and superstition, as the knife was an essential tool for survival since early man. Knife symbols can be found in various cultures to symbolize all stages of life; for example, a knife placed under the bed while giving birth is said to ease the pain, or, stuck into the headboard of a cradle, to protect the baby.; knives were included in some Anglo-Saxon burial rites, so the dead would not be defenseless in the next world. The knife plays an important role in some initiation rites, and many cultures perform rituals with a variety of knives, including the ceremonial sacrifices of animals. Samurai warriors, as part of bushido, could perform ritual suicide, or seppuku, with a tantō, a common Japanese knife. An athame, a ceremonial black-handled knife, is used in Wicca and derived forms of neopagan witchcraft. In Greece a black-handled knife placed under the pillow is used to keep away nightmares. As early as 1646 reference is made to a superstition of laying a knife across another piece of cutlery being a sign of witchcraft. A common belief is that if a knife is given as a gift, the relationship of the giver and recipient will be severed. Something such as a small coin or dove is exchanged for the gift, rendering "payment." Legislation. Knives are typically restricted by law, although restrictions vary greatly by country or state and type of knife. For example, some laws restrict carrying an unconcealed knife in public while other laws can restrict even private ownership of certain knives, such as switchblades.

apartment	knife
top 10 words in brain distribution (in article): build house state Unite public people service park building world	top 10 words in brain distribution (in article): iron blade steel handle cut metal tool nail hammer hand
top 10 words in brain distribution (not in article): city store street town home bus road village department country	top 10 words in brain distribution (not in article): head hair size whip breast design cell sword century bra
times more probable under apartment 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under knife (words not in the model)
An apartment'" is a self-contained housing unit that occupies only part of a building. Apartments may be owned (by an "owner occupier") or rented (by "tenants"). A common alternative term for apartment is flat'". The term "apartment" is favored in North America, whereas the term "flat" is commonly, but not exclusively, used in the United Kingdom, Ireland and the Commonwealth nations. In Malaysian English, "flat" often denotes a housing block of lesser quality meant for lower-income groups, while "apartment" is more generic and may also include luxury condominiums. In the US, some apartment-dwellers own their own apartments, either as co-ops, in which the residents own shares of a corporation that owns the building or development; or in condominiums, whose residents own their apartments and share ownership of the public spaces. Most apartments are in buildings designed for the purpose, but large older houses are sometimes divided into apartments. The word "apartment" connotes a residential unit or section in a building. In some locations, particularly the United States, the word denotes a rental unit owned by the building owner, and is not typically used for a condominium. In the UK, some flat owners own a share in the company that owns the freehold of the building. This is commonly known as a "share of freehold" flat. The freehold company has the right to collect annual ground rents from each of the flat owners in the building. The freeholder can also develop or sell the building, subject to the usual planning and restrictions that might apply. The word unit'" is a more general term referring to both apartments and rental business suites. The word is generally used only in the context of a specific building. E.g., "This building has three units" or "I'm going to rent a unit in this building", but not "I'm going to rent a unit somewhere." When there is no tenant occupying an apartment, the apartment owner or landlord is said to have a "vacancy". For apartment landlords, each vacancy represents a loss of income from rent-paying tenants for the time the apartment is vacant (i.e., unoccupied). Landlords' objectives are often to minimize the vacancy rate for their units. The owner of the apartment, typically when transferring possession to the occupant, gives him her the key to the apartment entrance and any other keys needed, such as a common key to the building or any other common areas and a mailbox key. When the occupant(s) move out, these keys are typically returned to the owner. Apartment types and characteristics. Apartments can be classified into several types. In the US the typical terms are a Studio'", "'efficiency'", bedsit, or bachelor style apartment. These all tend to be the smallest apartments with the cheapest rents in a given area. These kinds of apartment usually consist mainly of a large room which is the living, dining, and bedroom combined. There are usually kitchen facilities as part of this central room, but the bathroom is its own smaller separate room. Moving up from the efficiencies are "'one-bedroom apartments'", in which one bedroom is separate from the rest of the apartment. Then there are "'two-bedroom'", "'three-bedroom'", etc. apartments. Small apartments often have only one entrance. Large apartments often have two entrances, perhaps a door in the front and another in the back. Depending on the building design, the entrance doors may be directly to the outside or to a common area inside, such as a hallway. Depending on location, apartments may be available for rent "'furnished'" with furniture or "'unfurnished'" into which a tenant usually moves in with their own furniture. A "'garden apartment'" has some characteristics of a townhouse: each apartment has its own entrance, and apartments are not placed vertically over one another. However, a garden apartment is usually only one story high and never more than two stories; they are often one-bedrooms and almost never more than two-bedrooms. Some garden apartment buildings place a one-car garage under each apartment, with pedestrian entrances from a common courtyard open at one end. The grounds are more landscaped than for other modestly scaled apartments. (Alternately, "garden apartment" can refer to a unit built half below grade, putting its windows at garden level. Laundry facilities may be found in a common area accessible to all the tenants in the building, or each apartment may have its own facilities. Depending on when the building was built and the design of the building, utilities such as water, heating, and electricity may be common for all the apartments in the building or separate for each apartment and billed separately to each tenant (however, many areas in the US have ruled it illegal to split a water bill among all the tenants, especially if a pool is on the premises). Outlets for connection to telephones are typically included in apartments. Telephone service is optional and is practically always billed separately from the rent payments. Cable television and similar amenities are extra also. Parking space(s), air conditioner, and extra storage space may or may not be included with an apartment. Rental leases often limit the maximum number of people who can reside in each apartment. On or around the ground floor of the apartment building, a series of mailboxes are typically kept in a location accessible to the public and, thus, to the mailman too. Every unit typically gets its own mailbox with individual keys to it. Some very large apartment buildings with a full-time staff may take mail from the mailman and provide mail-sorting service. Near the mailboxes or some other location accessible by outsiders, there may be a buzzer (equivalent to a doorbell) for each individual unit. In smaller apartment buildings such as two- or three-flats, or even four-flats, garbage is often disposed of in trash containers similar to those used at houses. In larger buildings, garbage is often collected in a common trash bin or Dumpster. For cleanliness or minimizing noise, many lessors will place restrictions on tenants regarding keeping pets in an apartment. In some parts of the world, the word apartment refers to a new purpose-built self-contained residential unit in a building, whereas the word "flat" means a converted self-contained unit in an older building. An industrial, warehouse, or commercial space converted to an apartment is commonly called a loft. When part of a house is converted for the ostensible use of a landlord's family member, the unit may be known as an "in-law" apartment or "granny flat", though these (sometimes illegally) created units are often occupied by ordinary renters rather than family members. In Canada these suites are commonly located in the basements of houses and are therefore normally called "basement suites" or "mother-in-law suites." In Milwaukee vernacular architecture, a Polish flat is an existing small house or cottage that has been lifted up to accommodate the creation of a new basement floor housing a separate apartment, then set down again; thus becoming a modest two-story flat. In Russia, a communal apartment'" («коммуналка») is a room with a shared kitchen and bath. A typical arrangement is a cluster of five or so apartments with their common kitchen and bathroom and their own front door, occupying a floor in a pre-Revolutionary mansions. Traditionally a room is owned by the government and assigned to a family on a semi-permanent basis. It is possible to "privatize" a room by paying a large sum of money to the government; then it can legally be sold.	A knife'" is a handheld sharp-edged instrument consisting of a handle attached to a blade that is used for cutting. Knives were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools. History. The earliest knives were shaped by knapping (percussive flaking) of rock, particularly harder rocks such as obsidian and flint. During the Paleolithic era Homo habilis likely made similar tools out of wood, bone, and similar perishable materials that have not survived. As recent as five thousand years ago, as advances in metallurgy progressed, stone, wood, and bone blades were gradually succeeded by copper, bronze, iron, and eventually steel. The first metal (copper) knives were symmetrical double edged daggers, which copied the earlier flint daggers. In Europe the first single edged knives appeared during the middle bronze age. Modern knives may be made from many different materials such as alloy tool steels, carbon fiber, ceramics, and titanium. Materials and construction. Today, knives come in many forms but can be generally categorized between two broad types: fixed blade knives and folding, or pocket, knives. Modern knives consist of a "blade" (1'") and "handle" (2'"). The blade edge can be plain or serrated or a combination of both. The handle, used to grip and manipulate the blade safely, may include the "tang", a portion of the blade that extends into the handle. Knives are made with partial (extending part way into the handle) and full (extending the full length of the handle, often visible on top and bottom) tangs. The handle can also include a bolster, which is a piece of material used to balance the knife, usually brass or other metal, at the front of the handle where it meets the blade. The blade consists of the "point" (3'"), the end of the knife used for piercing, the "edge" (4'"), the cutting surface of the knife extending from the point to the heel, the "grind" (5'"), the "cross-section" shape of the blade, the "spine", (6'"), the top, thicker portion of the blade, the "fuller" (7'"), the groove added to lighten the blade, and the "ricasso" (8'"), the thick portion of the blade joining the blade and the handle. The "guard" (9'") is a barrier between the blade and the handle which protects the hand from an opponent, or the blade of the knife itself. A "choil", where the blade is unsharpened and possibly indented as it meets the handle, may be used to prevent scratches to the handle when sharpening or as a forward-finger grip. The end of the handle, or "butt" (10'"), may allow a "lanyard" (11'"), used to secure the knife to the wrist, or a portion of the tang to protrude as a striking surface for pounding or glass breaking. Blade. Knife blades can be manufactured from a variety of materials, each of which has advantages and disadvantages. Carbon steel, an alloy of iron and carbon, can be very sharp, hold its edge well, and remain easy to sharpen, but is vulnerable to rust and stains. Stainless steel is an alloy of iron, chromium, possibly nickel, and molybdenum, with only a small amount of carbon. It is not able to take quite as sharp an edge as carbon steel, but is highly resistant to corrosion. High carbon stainless steel is stainless steel with a higher amount of carbon, intended to incorporate the better attributes of carbon steel and stainless steel. High carbon stainless steel blades do not discolor or stain, and maintain a sharp edge. Laminate blades use multiple metals to create a layered sandwich, combining the attributes of both. For example, a harder, more brittle steel may be sandwiched between an outer layer of softer, tougher, stainless steel to reduce vulnerability to corrosion. In this case, however, the part most affected by corrosion, the edge, is still vulnerable. Pattern-welding is similar to laminate construction. Layers of different steel types are welded together, but then the stock is manipulated to create patterns in the steel. Titanium is metal that has a better strength-to-weight ratio, is more wear resistant, and more flexible than steel. Although less hard and unable to take as sharp an edge, carbides in the titanium alloy allow them to be heat-treated to a sufficient hardness. Ceramic blades are hard, brittle, and lightweight: they may maintain a sharp edge for years with no maintenance at all. They are immune to common corrosion, and can only be sharpened on silicon carbide sandpaper and some grinding wheels. Plastic blades are not especially sharp and typically serrated. They are often disposable. Steel blades are commonly shaped by forging or stock removal. Forged blades are made by heating a single piece of steel, then shaping the metal while hot using a hammer or press. Stock removal blades are shaped by grinding and removing metal. With both methods, after shaping, the steel must be heat treated. This involves heating the steel above its critical point, then quenching the blade to harden it. After hardening, the blade is tempered to remove stresses and make the blade tougher. Mass manufactured kitchen cutlery uses both the forging and stock removal processes. Forging tends to be reserved for manufacturers' more expensive product lines, and can often be distinguished from stock removal product lines by the presence of an integral bolster, though integral bolsters can be crafted through either shaping method. Knives are sharpened in various ways. Flat ground blades have a profile that tapers from the thick spine to the sharp edge in a straight or convex line. Seen in cross section, the blade would form a long, thin triangle, or where the taper does not extend to the back of the blade, a long thin rectangle with one peaked side. Hollow ground blades have concave, beveled edges. The resulting blade has a thinner edge, so it may have better cutting ability for shallow cuts, but it is lighter and less durable than flat ground blades and will tend to bind in deep cuts. Serrated blade knives have a wavy, scalloped or saw-like blade. Serrated blades are more well suited for tasks that require aggressive 'sawing' motions, whereas plain edge blades are better suited for tasks that require push-through cuts (e.g., shaving, chopping). Fixed blade features. A fixed blade knife does not fold or slide, and is typically stronger due to the tang, the extension of the blade into the handle, and lack of moving parts. Folding blade features. A folding knife connects the blade to the handle through a pivot, allowing the blade to fold into the handle. To prevent injury to the knife user through the blade accidentally closing on the user's hand, folding knives typically have a locking mechanism. Different locking mechanisms are favored by various individuals for reasons such as perceived strength (lock safety), legality, and ease of use. Another prominent feature on many folding knives is the opening mechanism. Traditional pocket knives and Swiss Army Knives commonly employ the nail nick, while modern folding knives more often use a stud, hole, disk, or "flipper" located on the blade, all which have the benefit of allowing the user to open the knife with one hand. "Automatic" or "switchblade" knives open using the stored energy from a spring that is released when the user presses a button or lever or other actuator built into the handle of the knife. Automatic knives are popular amongst law enforcement and military users for their ease of rapid deployment and their ability to be opened using only one hand. Automatic knives are severely restricted by law in most states. Increasingly common are "assisted opening" knives which use springs to propel the blade once the user has moved it past a certain angle. These differ from automatic or switchblade knives in that the blade is not released by means of a button or catch on the handle; rather, the blade itself is the actuator. Most assisted openers use flippers as their opening mechanism. Assisted opening knives can be as fast or faster than automatic knives to deploy. Sliding blade features. A sliding knife is a knife which can be opened by sliding the knife blade out the front of the handle. One method of opening is where the blade exits out the front of the handle point-first and then is locked into place (an example of the this is the gravity knife). Another form is a O-T-F (out-the-front) switchblade, which only requires the push of a button or spring to cause the blade to slide out of the handle, and lock into place. To retract the blade back into the handle, a release lever or button, usually the same control as to open, is pressed. A very common form of sliding knife is the sliding utility knife (commonly known as a stanley knife). Handle. The handles of knives can be made from a number of different materials, each of which has advantages and disadvantages. Handles are produced in a wide variety of shapes and styles. Handles are often textured to enhance grip. More exotic materials usually only seen on art or ceremonial knives include: Stone, bone, mammoth tooth, mammoth ivory, oosic (walrus penis bone), walrus tusk, antler (often called stag in a knife context), sheep horn, buffalo horn, teeth, etc. Many materials have been employed in knife handles. Knives as weapons. As a weapon, the knife is universally adopted as an essential tool. For example: Knives as utensils. A primary aspect of the knife as a tool includes dining, used either in food preparation or as cutlery. Examples of this include: Knives as tools. As a utility tool the knife can take many forms, including: Rituals and superstitions. The knife plays a significant role in some cultures through ritual and superstition, as the knife was an essential tool for survival since early man. Knife symbols can be found in various cultures to symbolize all stages of life; for example, a knife placed under the bed while giving birth is said to ease the pain, or, stuck into the headboard of a cradle, to protect the baby.; knives were included in some Anglo-Saxon burial rites, so the dead would not be defenseless in the next world. The knife plays an important role in some initiation rites, and many cultures perform rituals with a variety of knives, including the ceremonial sacrifices of animals. Samurai warriors, as part of bushido, could perform ritual suicide, or seppuku, with a tantō, a common Japanese knife. An athame, a ceremonial black-handled knife, is used in Wicca and derived forms of neopagan witchcraft. In Greece a black-handled knife placed under the pillow is used to keep away nightmares. As early as 1646 reference is made to a superstition of laying a knife across another piece of cutlery being a sign of witchcraft. A common belief is that if a knife is given as a gift, the relationship of the giver and recipient will be severed. Something such as a small coin or dove is exchanged for the gift, rendering "payment." Legislation. Knives are typically restricted by law, although restrictions vary greatly by country or state and type of knife. For example, some laws restrict carrying an unconcealed knife in public while other laws can restrict even private ownership of certain knives, such as switchblades.