History (from Greek ἱστορία, historia, meaning "inquiry; knowledge acquired by investigation") is the study of the past. Events before the invention of writing systems are considered prehistory. "History" is an umbrella term comprising past events as well as the memory, discovery, collection, organization, presentation, and interpretation of these events. Historians seek knowledge of the past using historical sources such as written documents, oral accounts, art and material artifacts, and ecological markers.History also includes the academic discipline which uses narrative to describe, examine, question, and analyze past events, and investigate their patterns of cause and effect. Historians often debate which narrative best explains an event, as well as the significance of different causes and effects. Historians also debate the nature of history as an end in itself, as well as its usefulness to give perspective on the problems of the present.Stories common to a particular culture, but not supported by external sources (such as the tales surrounding King Arthur), are usually classified as cultural heritage or legends. History differs from myth in that it is supported by evidence. However, ancient cultural influences have helped spawn variant interpretations of the nature of history which have evolved over the centuries and continue to change today. The modern study of history is wide-ranging, and includes the study of specific regions and the study of certain topical or thematic elements of historical investigation. History is often taught as part of primary and secondary education, and the academic study of history is a major discipline in university studies.
Herodotus, a 5th-century BC Greek historian, is often considered the "father of history" in the Western tradition, although he has also been criticized as the "father of lies". Along with his contemporary Thucydides, he helped form the foundations for the modern study of past events and societies. Their works continue to be read today, and the gap between the culture-focused Herodotus and the military-focused Thucydides remains a point of contention or approach in modern historical writing. In East Asia, a state chronicle, the Spring and Autumn Annals, was reputed to date from as early as 722 BC, although only 2nd-century BC texts have survived.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.A school is an educational institution designed to provide learning spaces and learning environments for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is sometimes compulsory. In these systems, students progress through a series of schools. The names for these schools vary by country (discussed in the Regional section below) but generally include primary school for young children and secondary school for teenagers who have completed primary education. An institution where higher education is taught, is commonly called a university college or university.
In addition to these core schools, students in a given country may also attend schools before and after primary (elementary in the US) and secondary (middle school in the US) education. Kindergarten or preschool provide some schooling to very young children (typically ages 3–5). University, vocational school, college or seminary may be available after secondary school. A school may be dedicated to one particular field, such as a school of economics or a school of dance. Alternative schools may provide nontraditional curriculum and methods.
Non-government schools, also known as private schools, may be required when the government does not supply adequate, or specific educational needs. Other private schools can also be religious, such as Christian schools, gurukula (Hindu schools), madrasa (Arabic schools), hawzas (Shi'i Muslim schools), yeshivas (Jewish schools), and others; or schools that have a higher standard of education or seek to foster other personal achievements. Schools for adults include institutions of corporate training, military education and training and business schools.
Critics of school often accuse the school system of failing to adequately prepare students for their future lifes, of encouraging certain temperaments while inhibiting others, of prescribing students exactly what to do, how, when, where and with whom, which would suppress creativity, and of using extrinsic measures such as grades and homework, which would inhibit children's natural curiosity and desire to learn.In homeschooling and distance education, teaching and learning take place independent from the institution of school or in a virtual school outside a traditional school building respectively. Schools are commonly organized in several different organizational models, including departmental, small learning communities, academies, integrated, and schools-within-a-school.
| תאריך המענק | 2021 |
|---|
| שפה מקורית | ???core.languages.en_GB??? |
|---|