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Adrenergic nerve fibre

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An adrenergic nerve fibre is a neuron for which the neurotransmitter is either adrenaline (epinephrine), noradrenaline or dopamine. These neurotransmitters are released at a location known as the synapse , which is a junction point between the axon of one nerve cell and the dendrite of another. The neurotransmitters are first released from the axon and then bind to the receptor site on the dendrite. Adrenergic nerve terminals are found in the secondary neurons of the sympathetic nervous system , one of two deviations of the autonomic nervous system which is responsible for your fight-or-flight response . This system increases heart rate , slows digestion , dilates pupils, and also controls the secretion of apocrine sweat glands in the dermal layer of skin, in addition to other responses. Composition The nerve fibre is a thread-like extension of a nerve cell that includes the axon which may or may not be encased in a myelinated sheath. The androgenic nerve fibre when myelinated increases the speed of transm ...more...



Optical fiber

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Fiber crew installing a 432-count fiber cable underneath the streets of Midtown Manhattan, New York City A TOSLINK fiber optic audio cable with red light being shone in one end transmits the light to the other end A wall-mount cabinet containing optical fiber interconnects. The yellow cables are single mode fibers ; the orange and aqua cables are multi-mode fibers : 50/125 µm OM2 and 50/125 µm OM3 fibers respectively. An optical fiber or optical fibre is a flexible, transparent fiber made by drawing glass ( silica ) or plastic to a diameter slightly thicker than that of a human hair . Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications , where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables. Fibers are used instead of metal wires because signals travel along them with less loss ; in addition, fibers are immune to electromagnetic interference , a problem from wh ...more...



Chromatin

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Chromatin is a complex of macromolecules found in cells, consisting of DNA , protein , and RNA . The primary functions of chromatin are 1) to package DNA into a more compact, denser shape, 2) to reinforce the DNA macromolecule to allow mitosis , 3) to prevent DNA damage, and 4) to control gene expression and DNA replication. The primary protein components of chromatin are histones that compact the DNA. Chromatin is only found in eukaryotic cells (cells with defined nuclei). Prokaryotic cells have a different organization of their DNA (the prokaryotic chromosome equivalent is called genophore and is localized within the nucleoid region ). Chromatin's structure is currently poorly understood despite being subjected to intense investigation. Its structure depends on several factors. The overall structure depends on the stage of the cell cycle . During interphase , the chromatin is structurally loose to allow access to RNA and DNA polymerases that transcribe and replicate the DNA. The local structure of chromati ...more...

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Skeletal muscle

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Skeletal muscle is one of three major muscle types, the others being cardiac muscle and smooth muscle . It is a form of striated muscle tissue which is under the 'voluntary' control of the somatic nervous system . Most skeletal muscles are attached to bones by bundles of collagen fibers known as tendons . A skeletal muscle refers to multiple bundles of cells called muscle fibers ( fascicles ). The fibres and muscles are surrounded by connective tissue layers called fasciae . Muscle fibres, or muscle cells , are formed from the fusion of developmental myoblasts in a process known as myogenesis . Muscle fibres are cylindrical, and have more than one nucleus . It has multiple mitochondria to meet energy needs. Muscle fibers are in turn composed of myofibrils . The myofibrils are composed of actin and myosin filaments, repeated in units called sarcomeres , which are the basic functional units of the muscle fiber. The sarcomere is responsible for the striated appearance of skeletal muscle, and forms the basic mac ...more...



Ground tissue

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The ground tissue of plants includes all tissues that are neither dermal nor vascular . It can be divided into three types based on the nature of the cell walls. 1 )Parenchyma cells have thin primary walls and usually remain alive after they become mature. Parenchyma forms the "filler" tissue in the soft parts of plants.usually present in cortex, pericycle, pith,and medullary rays in primary stem and root.2) Collenchyma cells have thin primary walls with some areas of secondary thickening. Collenchyma provides extra structural support, particularly in regions of new growth. 3 )Sclerenchyma cells have thick lignified secondary walls and often die when mature. Sclerenchyma provides the main structural support to a plant. Parenchyma Parenchyma ( ; from Greek παρέγχυμα parenkhyma, "visceral flesh" from παρεγχεῖν parenkhein, "to pour in" from παρα- para-, "beside", ἐν en-, "in" and χεῖν khein, "to pour") is a versatile ground tissue that generally constitutes the "filler" tissue in soft parts of plants. It form ...more...



Kenaf

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Kenaf [etymology: Persian], Hibiscus cannabinus , is a plant in the Malvaceae family also called Deccan hemp and Java jute . Hibiscus cannabinus is in the genus Hibiscus and is native to southern Asia , though its exact origin is unknown. The name also applies to the fibre obtained from this plant. Kenaf is one of the allied fibres of jute and shows similar characteristics. Common names Europe: French : chanvre de Bombay, chanvre du Deccan, chanvre de Guinée, chanvre de Gambo, chanvre de roselle, jute de Java, jute de Siam, kénaf, ketmie à feuilles de chanvre (Belgium), roselle German : Ambari, Dekkanhanf, Gambohanf, Hanfeibisch, Javajute, Kenaf, Rosellahanf, Roselle, Siamjute Portuguese : cânhamo rosella, juta-de-java, juta-do-sião, quenafe Spanish : cáñamo de la India, cáñamo de gambo, cáñamo Rosella, pavona encendida, yute de Java, yute de Siam Americas: Brazilian Portuguese: papoula-de-são-francisco, cânhamo-brasileiro, quenafe Africa: Afrikaans : stokroos Egypt & Northern Africa: til, teel, or teal ...more...



Oligosaccharide

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An oligosaccharide (from the Greek ὀλίγος olígos, "a few", and σάκχαρ sácchar, "sugar") is a saccharide polymer containing a small number (typically three to ten ) of monosaccharides (simple sugars). Oligosaccharides can have many functions including cell recognition and cell binding. For example, glycolipids have an important role in the immune response. They are normally present as glycans : oligosaccharide chains linked to lipids or to compatible amino acid side chains in proteins , by N- or O- glygosidic bonds . N-linked oligosaccharides are always pentasaccharides attached to asparagine via a beta linkage to the amine nitrogen of the side chain. Alternately, O-linked oligosaccharides are generally attached to threonine or serine on the alcohol group of the side chain. Not all natural oligosaccharides occur as components of glycoproteins or glycolipids. Some, such as the raffinose series, occur as storage or transport carbohydrates in plants. Others, such as maltodextrins or cellodextrins , result fro ...more...



Nerve

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A nerve is an enclosed, cable-like bundle of axons (nerve fibers, the long and slender projections of neurons ) in the peripheral nervous system . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons to peripheral organs. In the central nervous system , the analogous structures are known as tracts . Neurons are sometimes called nerve cells, though this term is potentially misleading since many neurons do not form nerves, and nerves also include non-neuronal Schwann cells that coat the axons in myelin . Each nerve is a cordlike structure containing bundles of axons. Within a nerve, each axon is surrounded by a layer of connective tissue called the endoneurium . The axons are bundled together into groups called fascicles , and each fascicle is wrapped in a layer of connective tissue called the perineurium . Finally, the entire nerve is wrapped in a layer of connective tissue called the epineurium . Anatomy Nerves are categorized into three group ...more...



Tendon

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A tendon or sinew is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension . Tendons are similar to ligaments ; both are made of collagen . Ligaments join one bone to another bone, while tendons connect muscle to bone. Structure Histologically, tendons consist of dense regular connective tissue fascicles encased in dense irregular connective tissue sheaths. Normal healthy tendons are composed mostly of parallel arrays of collagen fibers closely packed together. They are anchored to bone by Sharpey's fibres . The dry mass of normal tendons, which makes up about 30% of their total mass, is composed of about 86% collagen, 2% elastin , 1–5% proteoglycans , and 0.2% inorganic components such as copper , manganese , and calcium . The collagen portion is made up of 97–98% type I collagen, with small amounts of other types of collagen. These include type II collagen in the cartilaginous zones, type III collagen in the reticulin fibres of the vascular w ...more...



Solenoid (DNA)

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The solenoid structure of chromatin is a model for the structure of the 30 nm fibre. It is a secondary chromatin structure which helps to package eukaryotic DNA into the nucleus . Background Chromatin was first discovered by Walther Flemming by using aniline dyes to stain it. In 1974, it was first proposed by Roger Kornberg that chromatin was based on a repeating unit of a histone octamer and around 200 base pairs of DNA. The solenoid model was first proposed by John Finch and Aaron Klug in 1976. They used electron microscopy images and X-ray diffraction patterns to determine their model of the structure. This was the first model to be proposed for the structure of the 30 nm fibre. Structure DNA in the nucleus is wrapped around nucleosomes , which are histone octamers formed of core histone proteins; two histone H2A - H2B dimers, two histone H3 proteins, and two histone H4 proteins. The primary chromatin structure, the least packed form, is the 11 nm, or “beads on a string” form, where DNA is wrapped around ...more...



Olivocochlear system

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The olivocochlear system is a component of the auditory system involved with the descending control of the cochlea . Its nerve fibres, the olivocochlear bundle (OCB), form part of the vestibulocochlear nerve (VIIIth cranial nerve, also known as the auditory-vestibular nerve), and project from the superior olivary complex in the brainstem ( pons ) to the cochlea. Anatomy of the olivocochlear system Cell bodies of origin The mammalian olivocochlear bundle, divided into medial (red) and lateral (green) systems. Both contain crossed and uncrossed fibres. The predominant fibres are represented by a thicker line. The insert (far left) shows the position of the cell bodies of the MOCS and LOCS relative to the MSOC and LSOC respectively, as observed in mammals. The olivocochlear bundle (OCB) originates in the superior olivary complex in the brainstem. The vestibulocochlear anastomosis carries the efferent axons into the cochlea, where they innervate the organ of Corti (OC) . The OCB contains fibres projecting to both ...more...



Myosatellite cell

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Myosatellite cells or satellite cells are small multipotent cells with virtually no cytoplasm found in mature muscle . Satellite cells are precursors to skeletal muscle cells, able to give rise to satellite cells or differentiated skeletal muscle cells. They have the potential to provide additional myonuclei to their parent muscle fiber, or return to a quiescent state. More specifically, upon activation, satellite cells can re-enter the cell cycle to proliferate and differentiate into myoblasts . Myosatellite cells are located between the basement membrane and the sarcolemma of muscle fibers, and can lie in grooves either parallel or transversely to the longitudinal axis of the fibre. Their distribution across the fibre can vary significantly. Non-proliferative, quiescent myosatellite cells, which adjoin resting skeletal muscles, can be identified by their distinct location between sarcolemma and basal lamina, a high nuclear-to-cytoplasmic volume ratio, few organelles (e.g. ribosomes, endoplasmic reticulu ...more...



Mast cell

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A mast cell (also known as a mastocyte or a labrocyte ) is a type of white blood cell . Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a part of the immune and neuroimmune systems and contains many granules rich in histamine and heparin . Although best known for their role in allergy and anaphylaxis , mast cells play an important protective role as well, being intimately involved in wound healing, angiogenesis , immune tolerance , defense against pathogens , and blood–brain barrier function. The mast cell is very similar in both appearance and function to the basophil , another type of white blood cell . Although mast cells were once thought to be tissue resident basophils, it has been shown that the two cells develop from different hematopoietic lineages and thus cannot be the same cells. Origin and classification Illustration depicting mast cell activation and anaphylaxis Mast cell Mast cells were first described by Paul Ehrlich in his 1878 doctoral thesis on the basis ...more...



Pulmonary alveolus

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An alveolus (plural: alveoli , from Latin alveolus, "little cavity") is a hollow cavity found in the lung parenchyma , and is the basic unit of ventilation . Lung alveoli are the ends of the respiratory tree , branching from either alveolar sacs or alveolar ducts , which like alveoli are both sites of gas exchange with the blood as well. Alveoli are particular to mammalian lungs . Different structures are involved in gas exchange in other vertebrates. The alveolar membrane is the gas exchange surface. Carbon dioxide rich blood is pumped from the rest of the body into the capillaries that surround the alveoli where, through diffusion , carbon dioxide is released and oxygen absorbed. Structure The alveoli are located in the respiratory zone of the lungs, at the ends of the alveolar ducts and alveolar sac, representing the smallest units in the respiratory tract . They provide total surface area of about 75 m . Bronchial anatomy A typical pair of human lungs contain about 700 million alveoli, producing 70m of ...more...



Mercedes-Benz SLS AMG

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The Mercedes-Benz SLS AMG (C197 / R197) is a front mid-engine , 2-seater luxury , limited production supercar automobile developed by Mercedes-AMG of German automaker Mercedes-Benz and was the first Mercedes-Benz automobile designed in-house by AMG. The car, which has gull-wing doors , was the successor to the Mercedes-Benz SLR McLaren and was described by Mercedes-Benz as a spiritual successor to the Mercedes-Benz 300SL Gullwing . SLS stands for "Super Leicht Sport" (Super Light Sport). The Mercedes-Benz SLS AMG was assembled largely by hand, with its chassis and aluminum body shell produced by Magna Steyr in Graz, Austria and then transferred to Sindelfingen , Germany for assembly, with its engine being hand built by AMG in Affalterbach, Germany. It was the first Mercedes-Benz designed and built from scratch entirely by AMG. Upon its introduction the SLS AMG's 571 PS (420 kW; 563 hp) M159 engine was according to AMG "the world's most powerful naturally aspirated production series engine" ever produced. ...more...



Pulp mill

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A pulp mill is a manufacturing facility that converts wood chips or other plant fibre source into a thick fibre board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical or fully chemical methods ( kraft and sulfite processes). The finished product may be either bleached or non-bleached, depending on the customer requirements. Wood and other plant materials used to make pulp contain three main components (apart from water): cellulose fibres (desired for papermaking ), lignin (a three-dimensional polymer that binds the cellulose fibres together) and hemicelluloses , (shorter branched carbohydrate polymers). The aim of pulping is to break down the bulk structure of the fibre source, be it chips, stems or other plant parts, into the constituent fibres. Chemical pulping achieves this by degrading the lignin and hemicellulose into small, water-soluble molecules which can be washed away from the cellulose fibres without depolymerizing the cellulose f ...more...



Nocodazole

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Nocodazole is an antineoplastic agent which exerts its effect in cells by interfering with the polymerization of microtubules . Microtubules are one type of fibre which constitutes the cytoskeleton , and the dynamic microtubule network has several important roles in the cell, including vesicular transport, forming the mitotic spindle and in cytokinesis . Several drugs including vincristine and colcemid are similar to nocodazole in that they interfere with microtubule polymerization. Interestingly, nocodazole has been shown to decrease the oncogenic potential of cancer cells via another microtubules-independent mechanisms. Nocodazole stimulates the expression of LATS2 which potently inhibits the Wnt signaling pathway by abrogating the interaction between the Wnt-dependent transcriptional co-factors beta-catenin and BCL9 . It is related to mebendazole by replacement of the left most benzene ring by thiophene . Use in cell biology research As nocodazole affects the cytoskeleton, it is often used in cell biology ...more...



Cardiac muscle

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Cardiac muscle (heart muscle) is one of the three major types of muscle, the others being skeletal and smooth muscle . It is an involuntary, striated muscle that is found in the walls of the heart . This muscle tissue is known as myocardium , and forms a thick middle layer between the outer layer of the heart wall (the epicardium ) and the inner layer (the endocardium ). Myocardium is composed of individual heart muscle cells ( cardiomyocytes ) joined together by intercalated disks , encased by collagen fibres and other substances forming the extracellular matrix . Cardiac muscle contracts in a similar manner to skeletal muscle , albeit with some important differences. An electrical stimulation in the form of an action potential triggers the release of calcium from the cell's internal calcium store, the sarcoplasmic reticulum . The rise in calcium causes the cell's myofilaments to slide past each other in a process called excitation contraction coupling . Diseases of heart muscle are of major importance. Thes ...more...



Retina

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The retina is the third and inner coat of the eye which is a light-sensitive layer of tissue. The optics of the eye create an image of the visual world on the retina (through the cornea and lens), which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These are sent to various visual centres of the brain through the fibres of the optic nerve . Neural retina typically refers to three layers of neural cells (photo receptor cells, bipolar cells, and ganglion cells) within the retina, while the entire retina refers to these three layers plus a layer of pigmented epithelial cells. In vertebrate embryonic development , the retina and the optic nerve originate as outgrowths of the developing brain, specifically the embryonic diencephalon ; thus, the retina is considered part of the central nervous system (CNS) and is actually brain tissue. It is the only part of the CNS that can be visualiz ...more...



Spider silk

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A female specimen of Argiope bruennichi wraps her prey in silk. Indian summer by Józef Chełmoński (1875, National Museum in Warsaw ) depicts a peasant woman with a thread of gossamer in her hand. Spider cocoon Spider silk is a protein fibre spun by spiders . Spiders use their silk to make webs or other structures, which function as sticky nets to catch other animals, or as nests or cocoons to protect their offspring, or to wrap up prey. They can also use their silk to suspend themselves, to float through the air, or to glide away from predators. Most spiders vary the thickness and stickiness of their silk for different uses. In some cases, spiders may even use silk as a source of food. While methods have been developed to collect silk from a spider by force, it is difficult to gather silk from many spiders in a small space, in contrast to silkworm "farms". Biodiversity Uses All spiders produce silks, and a single spider can produce up to seven different types of silk for different uses. This is in contrast ...more...



Aschoff body

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In medicine , Aschoff bodies are nodules found in the hearts of individuals with rheumatic fever . They result from inflammation in the heart muscle and are characteristic of rheumatic heart disease. These nodules were discovered independently by Ludwig Aschoff and Paul Rudolf Geipel , and for this reason they are occasionally called Aschoff-Geipel bodies . Appearance Microscopically, Aschoff bodies are areas of inflammation of the connective tissue of the heart , or focal interstitial inflammation. Fully developed Aschoff bodies are granulomatous structures consisting of fibrinoid change, lymphocytic infiltration , occasional plasma cells , and characteristically abnormal macrophages surrounding necrotic centres. Some of these macrophages may fuse to form multinucleated giant cells . Others may become Anitschkow cells or "caterpillar cells", so named because of the appearance of their chromatin . They are pathognomic foci of fibrinoid necrosis found in many sites, most often the myocardium. Initially they ar ...more...



McLaren Automotive

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McLaren Automotive (often simply McLaren ) is a British automaker founded by Bruce McLaren and is based at the McLaren Technology Campus in Woking , Surrey . It produces and manufactures sports and luxury cars , usually produced in-house at designated production facilities. In July 2017, McLaren Automotive became 100% owned by the wider McLaren Technology Group . History Origin and founder McLaren Automotive replaced McLaren Cars in 2010. McLaren Cars was founded in 1985 by Ron Dennis , the company which went on to release the McLaren F1 in 1992. Between 1994 and 2010, McLaren Cars was registered as a 'dormant company', before the founding of McLaren Automotive in 2010. The new company was originally separate from the existing McLaren companies to enable investment in the new venture, but was brought together in July 2017 after Dennis sold his shares in McLaren Automotive and McLaren Technology Group . McLaren's Formula One founder Bruce McLaren was born in 1937, McLaren learned about cars and engineering a ...more...



Schwann cell

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Schwann cells (named after physiologist Theodor Schwann ) or neurolemmocytes are the principal glia of the peripheral nervous system (PNS). Glial cells function to support neurons and in the PNS, also include satellite cells , olfactory ensheathing cells , enteric glia and glia that reside at sensory nerve endings, such as the Pacinian corpuscle . There are two types of Schwann cell, myelinating and nonmyelinating. Myelinating Schwann cells wrap around axons of motor and sensory neurons to form the myelin sheath. The Schwann cell promoter is present in the downstream region of the human dystrophin gene that gives shortened transcript that are again synthesized in a tissue specific manner. During the development of the peripheral nervous system, the regulatory mechanisms of myelination are controlled via feedforward interaction of specific genes, influencing transcriptional cascades and shaping the morphology of the myelinated nerve fibers. Schwann cells are involved in many important aspects of peripheral ner ...more...



Group C nerve fiber

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Group C nerve fibers are one of three classes of nerve fiber in the central nervous system and peripheral nervous system . The C group fibers are unmyelinated and have a small diameter and low conduction velocity. They include postganglionic fibers in the autonomic nervous system (ANS), and nerve fibers at the dorsal roots (IV fiber). These fibers carry sensory information. Damage or injury to nerve fibers causes neuropathic pain . Capsaicin activates C fibre vanilloid receptors , giving chili peppers a hot sensation. Structure and anatomy Location C fibers are one class of nerve fiber found in the nerves of the somatic sensory system . They are afferent fibers , conveying input signals from the periphery to the central nervous system. Structure C fibers are unmyelinated unlike most other fibers in the nervous system. This lack of myelination is the cause of their slow conduction velocity , which is on the order of no more than 2  m/s . C fibers are on average 0.2-1.5 μm in diameter. Remak bundles C fiber ...more...



Odontoblast

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In vertebrates, an odontoblast is a cell of neural crest origin that is part of the outer surface of the dental pulp , and whose biological function is dentinogenesis , which is the formation of dentin , the substance beneath the tooth enamel on the crown and the cementum on the root. Origin Odontoblasts first appear at sites of tooth development at 17–18 weeks in utero and remain present until death unless killed by bacterial or chemical attack, or indirectly through other means such as heat or trauma (e.g. during dental procedures). Odontoblasts were originally the outer cells of the dental papilla. Thus, dentin and pulp tissue have similar embryological backgrounds, because both are originally derived from the dental papilla of the tooth germ. Structure Odontoblasts are large columnar cells, whose cell bodies are arranged along the interface between dentin and pulp, from the crown to cervix to the root apex in a mature tooth. The cell is rich in endoplasmic reticulum and Golgi complex, especially during pr ...more...



Autophagy

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(A) Diagram of autophagy; (B) Electron micrograph of autophagic structures in the fatbody of a fruit fly larva; (C) Fluorescently labeled autophagosomes in liver cells of starved mice. Autophagy (or autophagocytosis) (from the Ancient Greek αὐτόφαγος autóphagos, meaning "self-devouring" and κύτος kýtos, meaning "hollow" ) is the natural, regulated, destructive mechanism of the cell that disassembles unnecessary or dysfunctional components. Autophagy allows the orderly degradation and recycling of cellular components. In macroautophagy, targeted cytoplasmic constituents are isolated from the rest of the cell within a double-membraned vesicle known as an autophagosome . The autophagosome eventually fuses with lysosomes and the contents are degraded and recycled. Three forms of autophagy are commonly described: macroautophagy , microautophagy , and chaperone-mediated autophagy (CMA). In disease, autophagy has been seen as an adaptive response to stress, which promotes survival, whereas in other cases it app ...more...



Elastase

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Crystals of porcine elastase. In molecular biology , elastase is an enzyme from the class of proteases (peptidases) that break down proteins . Forms and classification Eight human genes exist for elastase: Family Gene symbol Protein name EC number Approved Previous Approved Previous chymotrypsin- like CELA1 ELA1 chymotrypsin-like elastase family, member 1 elastase 1, pancreatic EC 3.4.21.36 CELA2A ELA2A chymotrypsin-like elastase family, member 2A elastase 2A, pancreatic EC 3.4.21.71 CELA2B ELA2B chymotrypsin-like elastase family, member 2B elastase 2B, pancreatic EC 3.4.21.71 CELA3A ELA3A chymotrypsin-like elastase family, member 3A elastase 3A, pancreatic EC 3.4.21.70 CELA3B ELA3B chymotrypsin-like elastase family, member 3B elastase 3B, pancreatic EC 3.4.21.70 chymotrypsin CTRC ELA4 chymotrypsin C (caldecrin) elastase 4 EC 3.4.21.2 neutrophil ELANE ELA2 neutrophil elastase elastase 2 EC 3.4.21.37 macrophage MMP12 HME macrophage metalloelastase macrophage elastase EC 3.4.24.65 Some bacteria (including Pseud ...more...



Myometrium

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The myometrium is the middle layer of the uterine wall, consisting mainly of uterine smooth muscle cells (also called uterine myocytes ), but also of supporting stromal and vascular tissue. Its main function is to induce uterine contractions . Macrostructure The myometrium is located between the endometrium (the inner layer of the uterine wall), and the serosa or perimetrium (the outer uterine layer). Myometrium has 3 layers: outer longitudinal smooth muscles, middle crisscrossing (figure of eight) muscle fibres, and inner circular fibres. Middle crisscross fibres act as living ligature during involution of the uterus and prevent blood loss. The inner one-third of the myometrium (termed the junctional or sub-endometrial layer) appears to be derived from the Müllerian duct , while the outer, more predominant layer of the myometrium appears to originate from non-Müllerian tissue, and is the major contractile tissue during parturition and abortion. The junctional layer appears to function like a circular musc ...more...



Integumentary system

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The integumentary system comprises the skin and its appendages acting to protect the body from various kinds of damage, such as loss of water or abrasion from outside. The integumentary system includes hair , scales , feathers , hooves , and nails . It has a variety of additional functions; it may serve to waterproof, cushion, and protect the deeper tissues, excrete wastes, and regulate temperature , and is the attachment site for sensory receptors to detect pain, sensation, pressure, and temperature. In most land vertebrates with significant exposure to sunlight, the integumentary system also provides for vitamin D synthesis. Skin The skin is the largest organ in the body. In humans, it accounts for about 12 to 15 percent of total body weight and covers 1.5-2m of surface area. The human skin (integument) is composed of at least two major layers of tissue: the epidermis and dermis . (The hypodermis or subcutaneous layer is not part of the skin.) The epidermis is the outermost layer, providing the initial ...more...



Tramontana (sports car)

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The Tramontana Car is a mid-engined Spanish sports car with styling inspired by combining Formula One racing cars and jet-fighters . It is built by Atelier Tramontana , in Barcelona , Catalonia ( Spain ). It was launched as a concept at the 2005 Geneva Motor Show , and subsequently modified for production. It began as a project with the aim of breaking with conventionalisms and creating a new family of supercars . Only 12 a year are manufactured and they are all made under special request. In 2009, Tramontana introduced a closed top model named Tramontana R., and the XTR version in 2012. Now the company no longer produces these models, since they are focused on the Tramontana Car , which is a bespoke supercar fully customizable by the driver. Overview Engine and Transmission The car is fitted with either a mid-engined 5.5 litre double overhead cam V12 Mercedes-Benz , twin-turbocharged engine producing up to 900 PS (662 kW; 888 hp), or V10 naturally aspirated engine with 660 PS (485 kW; 651 hp). Before fit ...more...



Lead–acid battery

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The lead–acid battery was invented in 1859 by French physicist Gaston Planté and is the oldest type of rechargeable battery . Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio . These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by automobile starter motors . As they are inexpensive compared to newer technologies, lead–acid batteries are widely used even when surge current is not important and other designs could provide higher energy densities . Large-format lead–acid designs are widely used for storage in backup power supplies in cell phone towers, high-availability settings like hospitals, and stand-alone power systems . For these roles, modified versions of the standard cell may be used to improve storage times and reduce maintenance requirements. Gel-cells and absorbed glass-mat batteries a ...more...



Enterochromaffin cell

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Enterochromaffin (EC) cells (also known as Kulchitsky cells ), discovered by Nikolai Kulchitsky of Karazin Kharkiv National University . They are a type of enteroendocrine and neuroendocrine cell . They reside alongside the epithelium lining the lumen of the digestive tract and play a crucial role in gastrointestinal regulation, particularly intestinal motility and secretion. EC cells modulate neuron signalling in the enteric nervous system (ENS) via the secretion of the neurotransmitter serotonin and other peptides. As enteric afferent and efferent nerves do not protrude into the intestinal lumen, EC cells act as a form of sensory transduction. Serotonin in the ENS acts in synergy with other digestive hormones to regulate sensory and motor gastrointestinal reflexes. EC cells respond to both chemical and neurological stimuli. They are also reactive to mechanosensation and can be stimulated by a bolus moving through the bowel. Upon activation, EC cells release serotonin to act upon serotonin receptors on ENS ...more...



Hair cell

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Hair cells are the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates . Through mechanotransduction , hair cells detect movement in their environment. In mammals , the auditory hair cells are located within the spiral organ of Corti on the thin basilar membrane in the cochlea of the inner ear . They derive their name from the tufts of stereocilia called hair bundles that protrude from the apical surface of the cell into the fluid-filled cochlear duct . Mammalian cochlear hair cells are of two anatomically and functionally distinct types, known as outer, and inner hair cells. Damage to these hair cells results in decreased hearing sensitivity , and because the inner ear hair cells cannot regenerate , this damage is permanent. However, other organisms, such as the frequently studied zebrafish , and birds have hair cells that can regenerate. The human cochlea contains on the order of 3,500 inner hair cells and 12,000 outer hair cells at birth. The outer hai ...more...



Mordant

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Mordant red 19 is a typical mordant dye. Like many mordant dyes, it features the azo group (RN=NR) and various sites for chelating to metal cations . A French Indienne , a printed or painted textile in the manner of Indian productions, which used mordants to fix the dyes. A mordant or dye fixative is a substance used to set (i.e. bind) dyes on fabrics by forming a coordination complex with the dye, which then attaches to the fabric (or tissue). It may be used for dyeing fabrics or for intensifying stains in cell or tissue preparations. As applied to textiles, mordants are mainly of historical interest because the use of mordant dyes was largely displaced by directs . The term mordant comes from the present participle of French mordre, "to bite". In the past, it was thought that a mordant helped the dye bite onto the fiber so that it would hold fast during washing. A mordant is often a polyvalent metal ion , often chromium(III). The resulting coordination complex of dye and ion is colloidal and can be either ...more...



Myofibril

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A diagram of the structure of a myofibril (consisting of many myofilaments in parallel, and sarcomeres in series Sliding filament model of muscle contraction A myofibril (also known as a muscle fibril ) is a basic rod-like unit of a muscle cell. Muscles are composed of tubular cells called myocytes , known as muscle fibers in striated muscle , and these cells in turn contain many chains of myofibrils. They are created during embryonic development in a process known as myogenesis . Myofibrils are composed of long proteins including actin , myosin , and titin , and other proteins that hold them together. These proteins are organized into thick and thin filaments called myofilaments , which repeat along the length of the myofibril in sections called sarcomeres . Muscles contract by sliding the thick (myosin) and thin (actin) filaments along each other. Structure The filaments of myofibrils, myofilaments , consist of two types, thick and thin: Thin filaments consist primarily of the protein actin , coiled with n ...more...



Phenol formaldehyde resin

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Phenol formaldehyde resins (PF) or phenolic resins are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde . Used as the basis for Bakelite , PFs were the first commercial synthetic resins (plastics). They have been widely used for the production of molded products including billiard balls, laboratory countertops, and as coatings and adhesives . They were at one time the primary material used for the production of circuit boards but have been largely replaced with epoxy resins and fiberglass cloth, as with fire-resistant FR-4 circuit board materials. There are two main production methods. One reacts phenol and formaldehyde directly to produce a thermosetting network polymer , while the other restricts the formaldehyde to produce a prepolymer known as novolac which can be moulded and then cured with the addition of more formaldehyde and heat. There are many variations in both production and input materials that are used to produce a wide variety of resins for special ...more...



Alginate dressing

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An alginate dressing is a natural wound dressing derived from carbohydrate sources released by clinical bacterial species, in the same manner as biofilm formation. These types of dressings are best used on wounds that have a large amount of exudate . They may be use on full-thickness burns , surgical wounds , split-thickness graft donor sites , Mohs surgery defects , refractory decubiti , and chronic ulcers . They can also be applied onto dry wounds after normal saline is first applied to the site of application. Alginate dressings are produced from the calcium and sodium salts of alginic acid, a polysaccharide comprising mannuronic and guluronic acid units. Alginate is initially extracted from the cell wall of Brown seaweeds . Alginate dressings can be in the form of freeze-dried, porous (foam) sheets or flexible fibres. Flexible fibres are used to treat cavity wounds. The alginate will form a gel in contact with the exudates of the wound and give it a strong absorbent power. There is no evidence of superior ...more...



Vitreous body

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The vitreous body is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates . It is often referred to as the vitreous humour or simply "the vitreous". Structure The vitreous humour is a transparent, colorless, gelatinous mass that fills the space in the eye between the lens and the retina . It is surrounded by a layer of  collagen  called vitreous membrane separating it from the rest of the eye. it makes up four-fifths of the volume of the eyeball . The vitreous humour is fluid-like near the centre, and gel-like near the edges. The vitreous humour is in contact with the retina . It does not adhere to the retina, except at the optic nerve disc and the ora serrata (where the retina ends anteriorly), at the Wieger-band, the dorsal side of the lens. It is not connected at the macula , the area of the retina which provides finer detail and central vision. Aquaporin-4 in Müller cell in rats , transports water to the vitreous body. Anatomical features The v ...more...



RAI14

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Ankycorbin is a protein that in humans is encoded by the RAI14 gene . Ankycorbin has been associated with the cortical actin cytoskeleton structures in terminal web , cell-cell adhesion sites as well as stress fibres . References GRCh38: Ensembl release 89: ENSG00000039560 - Ensembl , May 2017 GRCm38: Ensembl release 89: ENSMUSG00000022246 - Ensembl , May 2017 "Human PubMed Reference:" . "Mouse PubMed Reference:" . Kutty RK, Kutty G, Samuel W, Duncan T, Bridges CC, El-Sherbeeny A, Nagineni CN, Smith SB, Wiggert B (May 2001). "Molecular characterization and developmental expression of NORPEG, a novel gene induced by retinoic acid". J Biol Chem. 276 (4): 2831–40. doi : 10.1074/jbc.M007421200 . PMID   11042181 . "Entrez Gene: RAI14 retinoic acid induced 14" . Peng YF, Mandai K, Sakisaka T, Okabe N, Yamamoto Y, Yokoyama S, Mizoguchi A, Shiozaki H, Monden M, Takai Y (December 2000). "Ankycorbin: a novel actin cytoskeleton-associated protein". Genes Cells. 5 (12): 1001–8. doi : 10.1046/j.1365-2443.2000.00381.x . ...more...



Radio over fiber

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Radio over fiber (RoF) or RF over fiber (RFoF) refers to a technology whereby light is modulated by a radio frequency signal and transmitted over an optical fiber link. Main technical advantages of using fiber optical links are lower transmission losses and reduced sensitivity to noise and electromagnetic interference compared to all-electrical signal transmission. Applications range from the transmission of mobile radio signals ( 3G , 4G , 5G and WiFi) and the transmission of cable television signals ( CATV ) to the transmission of RF L-Band signals in ground stations for satellite communications . General Advantage Low attenuation Signals transmitted on optical fiber attenuate much less than through other media like metal cables or wireless media. By using optical fiber, the radio signals can gap larger transmission distances, reducing the need of additional repeaters or amplifiers. Applications Wireless Communications In the area of Wireless Communications one main application is to facilitate wireless ac ...more...



10G-PON

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10G-PON (also known as XG-PON ) is a 2010 computer networking standard for data links , capable of delivering shared Internet access rates up to 10 Gbit/s (gigabits per second) over existing dark fiber . This is the ITU-T 's next generation standard following on from G-PON or Gigabit-capable PON. Optical fibre is shared by many subscribers in a network known as FTTx in a way that centralises most of the telecommunications equipment, often displacing copper phone lines that connect premises to the phone exchange. Passive optical network (PON) architecture has become a cost-effective way to meet performance demands in access networks , and sometimes also in large optical local networks for "Fibre-to-the-desk". Passive optical networks are used for the "Fibre-to-the-home" or "Fibre-to-the-premises" last mile with splitters that connect each central transmitter to many subscribers. The 10 Gbit/s shared capacity is the downstream speed broadcast to all users connected to the same PON, and the 2.5 Gbit/s upstream s ...more...



List of International Electrotechnical Commission standards

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This is an incomplete list of standards published by the International Electrotechnical Commission (IEC). The numbers of older IEC standards were converted in 1997 by adding 60000; for example IEC 27 became IEC 60027. IEC standards often have multiple sub-part documents; only the main title for the standard is listed here. IEC 60027 Letter symbols to be used in electrical technology IEC 60028 International standard of resistance for copper IEC 60034 Rotating electrical machines IEC 60038 IEC Standard Voltages IEC 60041 Field acceptance tests to determine the hydraulic performance of hydraulic turbines, storage pumps and pump-turbines IEC 60044 Instrument transformers IEC 60045 Steam turbines IEC 60050 International Electrotechnical Vocabulary IEC 60051 Direct acting indicating analogue electrical measuring instruments and their accessories IEC 60052 Voltage measurement by means of standard air gaps IEC 60055 Paper-insulated metal-sheathed cables for rated voltages up to 18/30 kV (with copper or aluminium cond ...more...



Elastin

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Elastin is a highly elastic protein in connective tissue and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of vertebrates and used in places where mechanical energy is required to be stored. In humans, elastin is encoded by the ELN gene . Function The ELN gene encodes a protein that is one of the two components of elastic fibers . The encoded protein is rich in hydrophobic amino acids such as glycine and proline , which form mobile hydrophobic regions bounded by crosslinks between lysine residues. Multiple transcript variants encoding different isoforms have been found for this gene. Elastin's soluble precursor is tropoelastin. The characterization of disorder is consistent with an entropy-driven mechanism of elastic recoil. It is concluded that conformational disorder is a constitutive feature of elastin structure and fun ...more...



McLaren 12C

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McLaren MP4-12C at Goodwood Festival of Speed 2010 Problems playing this file? See media help . The McLaren MP4-12C , later known simply as the McLaren 12C , is a sports car designed and manufactured by McLaren Automotive . It is the first production car wholly designed and built by McLaren since the McLaren F1 , which ended production in 1998. The car's final design was unveiled in September 2009, and was launched in mid-2011. The MP4-12C features a carbon fibre composite chassis, and is powered by a mid-mounted McLaren M838T 3.8-litre V8 , twin-turbo engine developing approximately 592 hp (441 kW; 600 PS) and around 443 lb·ft (601 N·m) of torque. The car makes use of Formula 1 -sourced technologies such as "brake steer", where the inside rear wheel is braked during fast cornering to reduce understeer . Power is transmitted to the wheels through a seven-speed shift dual-clutch gearbox. A convertible version of the car called the MP4-12C Spider , renamed the 12C Spider in 2012, is also available. In Februar ...more...



Stroma (tissue)

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Look up stroma in Wiktionary, the free dictionary. Stroma (from Greek στρῶμα, meaning “layer, bed, bed covering”) is the part of a tissue or organ that has a connective and structural role. It consists of all the parts which do not carry out the specific functions of the organ, for example, connective tissue, blood vessels, nerves, ducts, etc. The other part, the parenchyma , consists of the cells that perform the function of the tissue or organ. There are multiple ways of classifying tissues: one classification scheme is based on tissue functions and another analyzes their cellular components. Stromal tissue falls into the functional class that contributes to the body's support and movement. The cells which make up stroma tissues serve as a matrix in which the other cells are embedded. Stroma is made of various types of stromal cells . Examples of stroma include: stroma of iris stroma of cornea stroma of ovary stroma of thyroid gland stroma of thymus stroma of bone marrow lymph node stromal cell The connect ...more...



Muscle contraction

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Hierarchical organization of skeletal muscle Contractions of skeletal muscles allow vertebrate animals such as frogs to move Muscle contractions underlie movement Muscle contraction is the activation of tension -generating sites within muscle fibers . In physiology , muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length such as holding a heavy book or a dumbbell at the same position. The termination of muscle contraction is followed by muscle relaxation , which is a return of the muscle fibers to their low tension-generating state. Muscle contractions can be described based on two variables: length and tension. A muscle contraction is described as isometric if the muscle tension changes but the muscle length remains the same. In contrast, a muscle contraction is isotonic if muscle length changes but the muscle tension remains the same. If the muscle length shortens, the contraction is concentric; if the muscle lengt ...more...



Long-term depression

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Long-term depression ( LTD ), in neurophysiology , is an activity-dependent reduction in the efficacy of neuronal synapses lasting hours or longer following a long patterned stimulus. LTD occurs in many areas of the CNS with varying mechanisms depending upon brain region and developmental progress. LTD in the hippocampus and cerebellum have been the best characterized, but there are other brain areas in which mechanisms of LTD are understood. LTD has also been found to occur in different types of neurons that release various neurotransmitters, however, the most common neurotransmitter involved in LTD is L-glutamate. L-glutamate acts on the N-methyl-D- asparate receptors (NMDARs), α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPARs), kainate receptors (KARs) and metabotropic glutamate receptors (mGluRs) during LTD. It can result from strong synaptic stimulation (as occurs in the cerebellar Purkinje cells ) or from persistent weak synaptic stimulation (as in the hippocampus ). Long-term pot ...more...



Telecommunications in South Africa

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Suburban communication towers in Pretoria Telecommunications infrastructure in South Africa provides modern and efficient service to urban areas, including cellular and internet services. In 1997, Telkom , the South African telecommunications parastatal , was partly privatised and entered into a strategic equity partnership with a consortium of two companies, including SBC, a U.S. telecommunications company. In exchange for exclusivity (a monopoly ) to provide certain services for 5 years, Telkom assumed an obligation to facilitate network modernisation and expansion into the unserved areas. A Second Network Operator was to be licensed to compete with Telkom across its spectrum of services in 2002, although this license was only officially handed over in late 2005 and has recently begun operating under the name, Neotel . Four cellular companies provide service to over 30 million subscribers, with South Africa considered to have the 4th most advanced mobile telecommunications network worldwide. The four cellul ...more...



IBM BladeCenter

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The IBM BladeCenter was IBM 's blade server architecture, until it was replaced by Flex System . The x86 division was later sold to Lenovo in 2014. BladeCenter E front side: 8 blade servers (HS20) followed by 6 empty slots BladeCenter E back side, showing on the left two FC switches and two Ethernet switches . On the right side a management module with console cables. Magerit supercomputer ( CeSViMa ) has 86 Blade Centers (6 Blade Center E on each computing rack) History Introduced in 2002, based on engineering work started in 1999, the IBM BladeCenter was relatively late to the blade server market. It differed from prior offerings in that it offered a range of x86 Intel server processors and input/output (I/O) options. In February 2006, IBM introduced the BladeCenter H with switch capabilities for 10 Gigabit Ethernet and InfiniBand 4X. A web site called Blade.org was available for the blade computing community through about 2009. In 2012 the replacement Flex System was introduced. Versions IBM BladeCenter (E ...more...



Keloid

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Keloid , also known as keloid disorder and keloidal scar , is the formation of a type of scar which, depending on its maturity, is composed mainly of either type III (early) or type I (late) collagen . It is a result of an overgrowth of granulation tissue (collagen type 3) at the site of a healed skin injury which is then slowly replaced by collagen type 1. Keloids are firm, rubbery lesions or shiny, fibrous nodules , and can vary from pink to the color of the person's skin or red to dark brown in color. A keloid scar is benign and not contagious, but sometimes accompanied by severe itchiness, pain, and changes in texture. In severe cases, it can affect movement of skin. Keloid scars are seen 15 times more frequently in people of African descent than in people of European descent. Keloids should not be confused with hypertrophic scars , which are raised scars that do not grow beyond the boundaries of the original wound. Signs and symptoms Postoperative keloid on the wrist Keloids expand in claw-like growths ...more...




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