Описание
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to its widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives.In developed economies, about a third of plastic is used in packaging and roughly the same in buildings in applications such as piping, plumbing or vinyl siding. Other uses include automobiles (up to 20% plastic ), furniture, and toys. In the developing world, the applications of plastic may differ; 42% of India's consumption is used in packaging. In the medical field, polymer implants and other medical devices are derived at least partially from plastic. Worldwide, about 50 kg of plastic is produced annually per person, with production doubling every ten years.
The world's first fully synthetic plastic was Bakelite, invented in New York in 1907, by Leo Baekeland, who coined the term "plastics". Dozens of different types of plastics are produced today, such as polyethylene, which is widely used in product packaging, and polyvinyl chloride, used in construction and pipes because of its strength and durability. Many chemists have contributed to the materials science of plastics, including Nobel laureate Hermann Staudinger, who has been called "the father of polymer chemistry" and Herman Mark, known as "the father of polymer physics".The success and dominance of plastics starting in the early 20th century has caused widespread environmental problems, due to their slow decomposition rate in natural ecosystems. Toward the end of the 20th century, the plastics industry promoted recycling in order to ease environmental concerns while continuing to produce virgin plastic. The main companies producing plastics doubted the economic viability of recycling at the time, and this is reflected in contemporary plastic collection. Plastic collection and recycling is largely ineffective because of failures of contemporary decision-making mechanisms that resulted in a complexity and amount of cleaning and sorting post-consumer plastics too high for contemporary methods. Most plastic produced has not been reused, either being captured in landfills or persisting in the environment as plastic pollution. Plastic pollution can be found in all the world's major water bodies, for example, creating garbage patches in all of the world's oceans and contaminating terrestrial ecosystems.Surgery is a medical or dental specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pathological condition such as a disease or injury, to help improve bodily function, appearance, or to repair unwanted ruptured areas.
The act of performing surgery may be called a surgical procedure, operation, or simply "surgery". In this context, the verb "operate" means to perform surgery. The adjective surgical means pertaining to surgery; e.g. surgical instruments or surgical nurse. The person or subject on which the surgery is performed can be a person or an animal. A surgeon is a person who practices surgery and a surgeon's assistant is a person who practices surgical assistance. A surgical team is made up of the surgeon, the surgeon's assistant, an anaesthetist, a circulating nurse and a surgical technologist. Surgery usually spans from minutes to hours, but it is typically not an ongoing or periodic type of treatment. The term "surgery" can also refer to the place where surgery is performed, or, in British English, simply the office of a physician, dentist, or veterinarian.Discrimination is the act of making unjustified distinctions between human beings based on the groups, classes, or other categories to which they belong or are perceived to belong. People may be discriminated on the basis of race, gender, age, religion, or sexual orientation, as well as other categories. Discrimination especially occurs when individuals or groups are unfairly treated in a way which is worse than other people are treated, on the basis of their actual or perceived membership in certain groups or social categories. It involves restricting members of one group from opportunities or privileges that are available to members of another group.Discriminatory traditions, policies, ideas, practices and laws exist in many countries and institutions in all parts of the world, including territories where discrimination is generally looked down upon. In some places, attempts such as quotas have been used to benefit those who are believed to be current or past victims of discrimination. These attempts have often been met with controversy, and have sometimes been called reverse discrimination.Vegetarianism is the practice of abstaining from the consumption of meat (red meat, poultry, seafood, and the flesh of any other animal), and may also include abstention from by-products of animal slaughter.Vegetarianism may be adopted for various reasons. Many people object to eating meat out of respect for sentient life. Such ethical motivations have been codified under various religious beliefs, as well as animal rights advocacy. Other motivations for vegetarianism are health-related, political, environmental, cultural, aesthetic, economic, or personal preference. There are variations of the diet as well: an ovo-lacto vegetarian diet includes both eggs and dairy products, an ovo-vegetarian diet includes eggs but not dairy products, and a lacto-vegetarian diet includes dairy products but not eggs. A vegan diet excludes all animal products, including eggs and dairy. Avoidance of animal products may require dietary supplements to prevent deficiencies such as vitamin B12 deficiency, which leads to pernicious anemia. Psychologically, preference for vegetarian foods can be affected by one's own socio-economic status and evolutionary factors.Packaged and processed foods, such as cakes, cookies, candies, chocolate, yogurt, and marshmallows, often contain unfamiliar animal ingredients, and so may be a special concern for vegetarians due to the likelihood of such additives. Feelings among vegetarians vary concerning these ingredients. Some vegetarians scrutinize product labels for animal-derived ingredients, such as cheese made with rennet, while other vegetarians do not object to consuming them or are unaware of their presence.Semi-vegetarian diets consist largely of vegetarian foods but may include fish or poultry, or sometimes other meats, on an infrequent basis. Those with diets containing fish or poultry may define meat only as mammalian flesh and may identify with vegetarianism. A pescetarian diet has been described as "fish but no other meat".A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin modulus, a measure.
Representational models can be broadly divided into the concrete (e.g. physical form) and the abstract (e.g. behavioural patterns, especially as expressed in mathematical form). Of particular importance in the modern context, conceptual models are central to philosophy of science, as almost every scientific theory effectively embeds some kind of model of the physical or human sphere.
In commerce, a model might instead reference a specific version or configuration of a product offering, rather than functioning as a representation of something else.
In taxonomic settings (e.g. biology, architecture, art) a model is sometimes a particular instance of a set of related entities (species, built structures, artistic compositions) chosen as a convenient reference point around which to build discourse; such a model is almost always chosen to typify some central tendency of the group, exemplify the group's defining characteristic, or reify the group's historical lineage.
Kinds of models include:
The world's first fully synthetic plastic was Bakelite, invented in New York in 1907, by Leo Baekeland, who coined the term "plastics". Dozens of different types of plastics are produced today, such as polyethylene, which is widely used in product packaging, and polyvinyl chloride, used in construction and pipes because of its strength and durability. Many chemists have contributed to the materials science of plastics, including Nobel laureate Hermann Staudinger, who has been called "the father of polymer chemistry" and Herman Mark, known as "the father of polymer physics".The success and dominance of plastics starting in the early 20th century has caused widespread environmental problems, due to their slow decomposition rate in natural ecosystems. Toward the end of the 20th century, the plastics industry promoted recycling in order to ease environmental concerns while continuing to produce virgin plastic. The main companies producing plastics doubted the economic viability of recycling at the time, and this is reflected in contemporary plastic collection. Plastic collection and recycling is largely ineffective because of failures of contemporary decision-making mechanisms that resulted in a complexity and amount of cleaning and sorting post-consumer plastics too high for contemporary methods. Most plastic produced has not been reused, either being captured in landfills or persisting in the environment as plastic pollution. Plastic pollution can be found in all the world's major water bodies, for example, creating garbage patches in all of the world's oceans and contaminating terrestrial ecosystems.Surgery is a medical or dental specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pathological condition such as a disease or injury, to help improve bodily function, appearance, or to repair unwanted ruptured areas.
The act of performing surgery may be called a surgical procedure, operation, or simply "surgery". In this context, the verb "operate" means to perform surgery. The adjective surgical means pertaining to surgery; e.g. surgical instruments or surgical nurse. The person or subject on which the surgery is performed can be a person or an animal. A surgeon is a person who practices surgery and a surgeon's assistant is a person who practices surgical assistance. A surgical team is made up of the surgeon, the surgeon's assistant, an anaesthetist, a circulating nurse and a surgical technologist. Surgery usually spans from minutes to hours, but it is typically not an ongoing or periodic type of treatment. The term "surgery" can also refer to the place where surgery is performed, or, in British English, simply the office of a physician, dentist, or veterinarian.Discrimination is the act of making unjustified distinctions between human beings based on the groups, classes, or other categories to which they belong or are perceived to belong. People may be discriminated on the basis of race, gender, age, religion, or sexual orientation, as well as other categories. Discrimination especially occurs when individuals or groups are unfairly treated in a way which is worse than other people are treated, on the basis of their actual or perceived membership in certain groups or social categories. It involves restricting members of one group from opportunities or privileges that are available to members of another group.Discriminatory traditions, policies, ideas, practices and laws exist in many countries and institutions in all parts of the world, including territories where discrimination is generally looked down upon. In some places, attempts such as quotas have been used to benefit those who are believed to be current or past victims of discrimination. These attempts have often been met with controversy, and have sometimes been called reverse discrimination.Vegetarianism is the practice of abstaining from the consumption of meat (red meat, poultry, seafood, and the flesh of any other animal), and may also include abstention from by-products of animal slaughter.Vegetarianism may be adopted for various reasons. Many people object to eating meat out of respect for sentient life. Such ethical motivations have been codified under various religious beliefs, as well as animal rights advocacy. Other motivations for vegetarianism are health-related, political, environmental, cultural, aesthetic, economic, or personal preference. There are variations of the diet as well: an ovo-lacto vegetarian diet includes both eggs and dairy products, an ovo-vegetarian diet includes eggs but not dairy products, and a lacto-vegetarian diet includes dairy products but not eggs. A vegan diet excludes all animal products, including eggs and dairy. Avoidance of animal products may require dietary supplements to prevent deficiencies such as vitamin B12 deficiency, which leads to pernicious anemia. Psychologically, preference for vegetarian foods can be affected by one's own socio-economic status and evolutionary factors.Packaged and processed foods, such as cakes, cookies, candies, chocolate, yogurt, and marshmallows, often contain unfamiliar animal ingredients, and so may be a special concern for vegetarians due to the likelihood of such additives. Feelings among vegetarians vary concerning these ingredients. Some vegetarians scrutinize product labels for animal-derived ingredients, such as cheese made with rennet, while other vegetarians do not object to consuming them or are unaware of their presence.Semi-vegetarian diets consist largely of vegetarian foods but may include fish or poultry, or sometimes other meats, on an infrequent basis. Those with diets containing fish or poultry may define meat only as mammalian flesh and may identify with vegetarianism. A pescetarian diet has been described as "fish but no other meat".A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin modulus, a measure.
Representational models can be broadly divided into the concrete (e.g. physical form) and the abstract (e.g. behavioural patterns, especially as expressed in mathematical form). Of particular importance in the modern context, conceptual models are central to philosophy of science, as almost every scientific theory effectively embeds some kind of model of the physical or human sphere.
In commerce, a model might instead reference a specific version or configuration of a product offering, rather than functioning as a representation of something else.
In taxonomic settings (e.g. biology, architecture, art) a model is sometimes a particular instance of a set of related entities (species, built structures, artistic compositions) chosen as a convenient reference point around which to build discourse; such a model is almost always chosen to typify some central tendency of the group, exemplify the group's defining characteristic, or reify the group's historical lineage.
Kinds of models include:
| Данные стали доступны | 2021 |
|---|---|
| Издатель | South Park Foreign Language Education Press |