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Natural Experiment
A natural experiment is a study in which individuals (or clusters of individuals) are exposed to the experimental and control conditions that are determined by nature or by other factors outside the control of the investigators. The process governing the exposures arguably resembles random assignment. Thus, natural experiments are ''observational studies'' and are not controlled in the traditional sense of a randomized experiment (an ''intervention study''). Natural experiments are most useful when there has been a clearly defined exposure involving a well defined subpopulation (and the absence of exposure in a similar subpopulation) such that changes in outcomes may be plausibly attributed to the exposure. In this sense, the difference between a natural experiment and a non-experimental observational study is that the former includes a comparison of conditions that pave the way for causal inference, but the latter does not. Natural experiments are employed as study designs whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Experiment
An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Experiments vary greatly in goal and scale but always rely on repeatable procedure and logical analysis of the results. There also exist natural experimental studies. A child may carry out basic experiments to understand how things fall to the ground, while teams of scientists may take years of systematic investigation to advance their understanding of a phenomenon. Experiments and other types of hands-on activities are very important to student learning in the science classroom. Experiments can raise test scores and help a student become more engaged and interested in the material they are learning, especially when used over time. Experiments can vary from personal and informal natural comparisons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Snow (physician)
John Snow (15 March 1813 – 16 June 1858) was an English physician and a leader in the development of anaesthesia and Hygiene#Medical hygiene, medical hygiene. He is considered one of the founders of modern epidemiology and early Germ theory of disease, germ theory, in part because of his work in tracing the source of a 1854 Broad Street cholera outbreak, cholera outbreak in London's Soho, which he identified as a particular public water pump. Snow's findings inspired fundamental changes in the water and Great Stink, waste systems of London, which led to similar changes in other cities, and a significant improvement in general public health around the world. Early life and education Snow was born on 15 March 1813 in York, England, the first of nine children born to William and Frances Snow in their North Street (York), North Street home, and was baptised at All Saints' Church, North Street, York. His father was a labourer who worked at a local coal yard, by the Ouse, const ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Weapons Testing
Nuclear weapons tests are experiments carried out to determine the performance of nuclear weapons and the effects of Nuclear explosion, their explosion. Nuclear testing is a sensitive political issue. Governments have often performed tests to signal strength. Because of their destruction and fallout, testing has seen opposition by civilians as well as governments, with international bans having been agreed on. Thousands of tests have been performed, with most in the second half of the 20th century. The first nuclear device was detonated as a test by the United States at the Trinity site in New Mexico on July 16, 1945, with a yield approximately TNT equivalent, equivalent to 20 kilotons of TNT. The first thermonuclear weapon technology test of an engineered device, codenamed Ivy Mike, was tested at the Enewetak Atoll in the Marshall Islands on November 1, 1952 (local date), also by the United States. The largest nuclear weapon ever tested was the Tsar Bomba of the Soviet Union at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crossover Study
In medicine, a crossover study or crossover trial is a longitudinal study in which subjects receive a sequence of different treatments (or exposures). While crossover studies can be observational studies, many important crossover studies are controlled experiments, which are discussed in this article. Crossover designs are common for experiments in many scientific disciplines, for example psychology, pharmaceutical science, and medicine. Randomized, controlled crossover experiments are especially important in health care. In a randomized clinical trial, the subjects are randomly assigned to different arms of the study which receive different treatments. When the trial has a repeated measures design, the same measures are collected multiple times for each subject. A crossover trial has a repeated measures design in which each patient is assigned to a sequence of two or more treatments, of which one may be a standard treatment or a placebo. Nearly all crossover are designed to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Medical Journal
''The BMJ'' is a fortnightly peer-reviewed medical journal, published by BMJ Publishing Group Ltd, which in turn is wholly-owned by the British Medical Association (BMA). ''The BMJ'' has editorial freedom from the BMA. It is one of the world's oldest general medical journals. Previously called the ''British Medical Journal'', the title was officially shortened to ''BMJ'' in 1988, and then changed to ''The BMJ'' in 2014. The current editor-in-chief of ''The BMJ'' is Kamran Abbasi, who was appointed in January 2022. History The journal began publishing on 3 October 1840 as the ''Provincial Medical and Surgical Journal'' and quickly attracted the attention of physicians around the world through its publication of high-quality original research articles and unique case reports. The ''BMJ''s first editors were P. Hennis Green, lecturer on the diseases of children at the Hunterian School of Medicine, who also was its founder, and Robert Streeten of Worcester, a member of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myocardial Infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom is retrosternal Angina, chest pain or discomfort that classically radiates to the left shoulder, arm, or jaw. The pain may occasionally feel like heartburn. This is the dangerous type of acute coronary syndrome. Other symptoms may include shortness of breath, nausea, presyncope, feeling faint, a diaphoresis, cold sweat, Fatigue, feeling tired, and decreased level of consciousness. About 30% of people have atypical symptoms. Women more often present without chest pain and instead have neck pain, arm pain or feel tired. Among those over 75 years old, about 5% have had an MI with little or no history of symptoms. An MI may cause heart failure, an Cardiac arrhythmia, irregular heartbeat, cardiogenic shock or cardiac arrest. Most MIs occur d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smoking Ban
Smoking bans, or smoke-free laws, are public policies, including criminal laws and occupational safety and health regulations, that prohibit tobacco smoking in certain spaces. The spaces most commonly affected by smoking bans are indoor employment, workplaces and buildings open to the public such as restaurants, Bar (establishment), bars, office buildings, schools, retail stores, hospitals, libraries, transport facilities, and government buildings, in addition to public transport vehicles such as aircraft, buses, watercraft, and trains. However, laws may also prohibit smoking in outdoor areas such as parks, beaches, pedestrian plazas, college and hospital campuses, and within a certain distance from the entrance to a building, and in some cases, private vehicles and multi-unit residences. The most common rationale cited for restrictions on smoking is the negative health effects associated with secondhand smoke (SHS), or the inhalation of tobacco smoke by persons who are not smo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helena, Montana
Helena (; ) is the List of capitals in the United States, capital city of the U.S. state of Montana and the county seat, seat of Lewis and Clark County, Montana, Lewis and Clark County. Helena was founded as a gold camp during the Montana gold rush, and established on October 30, 1864. Due to the gold rush, Helena became a wealthy city, with approximately 50 millionaires inhabiting the area by 1888. The concentration of wealth contributed to the city's prominent, elaborate Victorian architecture. At the 2020 United States census, 2020 census Helena's population was 32,091, making it the 5th least populous state capital in the United States and the List of cities and towns in Montana, 6th most populous city in Montana. It is the principal city of the Helena, Montana metropolitan area, Helena Metropolitan Statistical Area, which includes all of Lewis and Clark, and Jefferson County, Montana, Jefferson counties; the MSA's population being 83,058 according to the 2020 census. The l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Economic Review
The ''American Economic Review'' is a monthly peer-reviewed academic journal first published by the American Economic Association in 1911. The current editor-in-chief is Erzo FP Luttmer, a professor of economics at Dartmouth College. The journal is based in Pittsburgh. It is one of the " top five" journals in economics. In 2004, the ''American Economic Review'' began requiring "data and code sufficient to permit replication" of a paper's results, which is then posted on the journal's website. Exceptions are made for proprietary data. Until 2017, the May issue of the ''American Economic Review'', titled the ''Papers and Proceedings'' issue, featured the papers presented at the American Economic Association's annual meeting that January. After being selected for presentation, the papers in the ''Papers and Proceedings'' issue did not undergo a formal process of peer review. Starting in 2018, papers presented at the annual meetings have been published in a separate journal, '' AEA Pap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David A
David (; , "beloved one") was a king of ancient Israel and Judah and the third king of the United Monarchy, according to the Hebrew Bible and Old Testament. The Tel Dan stele, an Aramaic-inscribed stone erected by a king of Aram-Damascus in the late 9th/early 8th centuries BCE to commemorate a victory over two enemy kings, contains the phrase (), which is translated as " House of David" by most scholars. The Mesha Stele, erected by King Mesha of Moab in the 9th century BCE, may also refer to the "House of David", although this is disputed. According to Jewish works such as the '' Seder Olam Rabbah'', '' Seder Olam Zutta'', and '' Sefer ha-Qabbalah'' (all written over a thousand years later), David ascended the throne as the king of Judah in 885 BCE. Apart from this, all that is known of David comes from biblical literature, the historicity of which has been extensively challenged,Writing and Rewriting the Story of Solomon in Ancient Israel; by Isaac Kalimi; page 3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambeth Waterworks Company
The Lambeth Waterworks Company was a utility company supplying water to parts of south London in England. The company was established in 1785 with works in north Lambeth and became part of the publicly owned Metropolitan Water Board in 1904. Origins The Lambeth Waterworks Company, founded by the ( 25 Geo. 3. c. 89) to supply water to south and west London, established premises on the south bank of the River Thames close to the present site of Hungerford Bridge where the Royal Festival Hall now stands. The company's first water-intake lay on the south side of the river, supplied directly from the river. After complaints that the water was foul, the intake was moved to the middle of the river. The Company expanded to supply Kennington in 1802 and about this time replaced its wooden pipes with iron ones. Infrastructure In 1832 the company built a reservoir at Streatham Hill, and then obtained the ( 4 & 5 Will. 4. c. vii) to extend its area of supply. In the same year the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sewage
Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewerage, sewer system. Sewage consists of wastewater discharged from residences and from commercial, institutional and public facilities that exist in the locality. Text was copied from this source, which is available under a creativecommons:by/4.0/, Creative Commons Attribution 4.0 International License Sub-types of sewage are greywater (from sinks, bathtubs, showers, dishwashers, and clothes washers) and blackwater (waste), blackwater (the water used to flush toilets, combined with the human waste that it flushes away). Sewage also contains soaps and detergents. Food waste may be present from dishwashing, and food quantities may be increased where garbage disposal units are used. In regions where toilet paper is used rather than bidets, that paper is also added to the sewage. Sewage contains macro-pollu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
