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Mad Cow Crisis
The mad cow crisis is a Health crisis, health and socio-economic crisis characterized by the collapse of beef consumption in the 1990s, as consumers became concerned about the transmission of bovine spongiform encephalopathy (BSE) to humans through the ingestion of this type of meat. Background Bovine spongiform encephalopathy, BSE is a degenerative infection of the central nervous system in cattle. It is a fatal disease, similar to scrapie in sheep and goats, caused by a prion. A major epizootic affected the UK, and to a lesser extent a number of other countries, between 1986 and the 2000s, infecting more than 190,000 animals, not counting those that remained undiagnosed. The epidemic is thought to have originated in the feeding of cattle with meat and bone meal, obtained from the uneaten parts of cattle and animal cadavers. The epidemic took a particular turn when scientists realized in 1996 that the disease could be transmitted to humans through the consumption of meat pr ...
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Aphis
''Aphis'' is a genus of insects in the family Aphididae containing at least 600 species of aphids. It includes many notorious agricultural pests, such as the soybean aphid ''Aphis glycines''. Many species of ''Aphis'', such as '' A. coreopsidis'' and '' A. fabae'', are myrmecophiles, forming close associations with ants. Selected Species *'' Aphis affinis'' *''Aphis asclepiadis'' — milkweed aphid *''Aphis craccae'' — tufted vetch aphid *''Aphis craccivora'' — cowpea aphid *'' Aphis fabae'' — black bean aphid *''Aphis genistae'' *''Aphis gossypii'' — cotton aphid *''Aphis glycines'' — soybean aphid *''Aphis helianthi'' — sunflower aphid *'' Aphis nerii'' — oleander aphid *''Aphis pomi'' — apple aphid *'' Aphis rubicola'' — small raspberry aphid *'' Aphis spiraecola'' — spirea aphid (syn. ''Aphis citricola'' — citrus aphid) *'' Aphis valerianae'' — black valerian aphid See also * List of Aphis species Photos Image:Aphis citricola1.jpg, '' Aphis c ...
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Astrocyte
Astrocytes (from Ancient Greek , , "star" + , , "cavity", "cell"), also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord. They perform many functions, including biochemical control of endothelial cells that form the blood–brain barrier, provision of nutrients to the nervous tissue, maintenance of extracellular ion balance, regulation of cerebral blood flow, and a role in the repair and scarring process of the brain and spinal cord following infection and traumatic injuries. The proportion of astrocytes in the brain is not well defined; depending on the counting technique used, studies have found that the astrocyte proportion varies by region and ranges from 20% to 40% of all glia. Another study reports that astrocytes are the most numerous cell type in the brain. Astrocytes are the major source of cholesterol in the central nervous system. Apolipoprotein E transports cholesterol from astrocytes to neurons and other gli ...
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Knacker
A knacker (), knackerman or knacker man is a person who removes and clears animal carcasses (dead, dying, injured) from private farms or public highways and renders the collected carcasses into by-products such as fats, tallow ( yellow grease), glue, gelatin, bone meal, bone char, sal ammoniac, soap, bleach and animal feed. A knacker's yard or a knackery is different from a slaughterhouse or abattoir, where animals are slaughtered for human consumption. Since the Middle Ages, the occupation of "knacker man" was frequently considered a disreputable occupation. Knackers were often also commissioned by the courts as public executioners. Etymology The oldest recorded use of the word "knacker" dates to 1812, meaning "one who slaughters old or sick horses" and in 1855 "to kill, castrate", and is believed to be the same word as the earlier knacker/nacker "harness-maker" from the 1570s, surviving in 18th century dialects. The sense extension is perhaps because "knackers" provid ...
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Endemism
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be ''endemic'' to that particular part of the world. An endemic species can be also be referred to as an ''endemism'' or in scientific literature as an ''endemite''. For example ''Cytisus aeolicus'' is an endemite of the Italian flora. ''Adzharia renschi'' was once believed to be an endemite of the Caucasus, but it was later discovered to be a non-indigenous species from South America belonging to a different genus. The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range. A rare alternative term for a species that is endemic is "precinctive", which applies t ...
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Sterilization (microbiology)
Sterilization refers to any process that removes, kills, or deactivates all forms of life (particularly microorganisms such as fungi, bacteria, spores, and unicellular eukaryotic organisms) and other biological agents such as prions present in or on a specific surface, object, or fluid. Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization, in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, an object is referred to as being sterile or aseptic. Applications Foods One of the first steps toward modernized sterilization was made by Nicolas Appert, who discovered that application of heat over a suitable period slowed the decay of foods and various liquids, preserving them for safe consumption for a longer time than was typical. Canning of foods is an extension ...
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Pasteurization
Pasteurization or pasteurisation is a process of food preservation in which packaged and non-packaged foods (such as milk and fruit juices) are treated with mild heat, usually to less than , to eliminate pathogens and extend shelf life. The process is intended to destroy or deactivate microorganisms and enzymes that contribute to food spoilage or risk of disease, including vegetative bacteria, but most bacterial spores survive the process. The process is named after the French microbiologist Louis Pasteur whose research in the 1860s demonstrated that thermal processing would deactivate unwanted microorganisms in wine. Spoilage enzymes are also inactivated during pasteurization. Today, pasteurization is used widely in the dairy industry and other food processing industries to achieve food preservation and food safety. By the year 1999, most liquid products were heat treated in a continuous system where heat can be applied using a plate heat exchanger or the direct or ...
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Desiccation
Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. Industry Desiccation is widely employed in the oil and gas industry. These materials are obtained in a hydrated state, but the water content leads to corrosion or is incompatible with downstream processing. Removal of water is achieved by cryogenic condensation, absorption into glycols, and absorption onto desiccants such as silica gel. Laboratory A desiccator is a heavy glass or plastic container, now somewhat antiquated, used in practical chemistry for drying or keeping small amounts of materials very dry. The material is placed on a shelf, and a drying agent or ''desiccant'', such as dry silica gel or anhydrous sodium hydroxide, is placed below the shelf. Often some sort of humidity indicator is included in the desiccator to s ...
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Neuron
A neuron, neurone, or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology), cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all Animalia, animals except sponges and placozoa. Non-animals like plants and fungi do not have nerve cells. Neurons are typically classified into three types based on their function. Sensory neurons respond to Stimulus (physiology), stimuli such as touch, sound, or light that affect the cells of the Sense, sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to gland, glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. When multiple neurons are connected together, they form what is called a neural circuit. A typical neuron consists of a cell bo ...
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Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid resid ...
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Grass Tetany
Grass tetany is a metabolic disease involving magnesium deficiency, which can occur in such ruminant livestock as beef cattle, dairy cattle and sheep, usually after grazing on pastures of rapidly growing grass, especially in early spring. Symptoms and cause Progressive symptoms may include grazing away from the herd, irritability, muscle twitching, staring, incoordination, staggering, collapse, thrashing, head thrown back, and coma, followed by death. However, clinical signs are not always evident before the animal is found dead. The condition results from hypomagnesemia (low magnesium concentration in blood) which may reflect low magnesium intake, low magnesium absorption, unusually low retention of magnesium, or a combination of these. Commonly, apparent symptoms develop only when hypomagnesemia is accompanied by hypocalcemia (blood Ca below 8 mg/dL). Low magnesium intake by grazing ruminants may occur especially with some grass species early in the growing season, due ...
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Tachycardia
Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (such as with exercise) or abnormal (such as with electrical problems within the heart). Complications Tachycardia can lead to fainting. When the rate of blood flow becomes too rapid, or fast blood flow passes on damaged endothelium, it increases the friction within vessels resulting in turbulence and other disturbances. According to the Virchow's triad, this is one of the three conditions that can lead to thrombosis (i.e., blood clots within vessels). Causes Some causes of tachycardia include: * Adrenergic storm * Anaemia * Anxiety * Atrial fibrillation * Atrial flutter * Atrial tachycardia * Atrioventricular reentrant tachycardia * AV nodal reentrant tachycardia * Brugada syndrome * Circulatory shock and its various ca ...
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