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Metachronal Rhythm
A metachronal rhythm or metachronal wave refers to wavy movements produced by the sequential action (as opposed to synchronized) of structures such as cilia, segments of worms, or legs. These movements produce the appearance of a travelling wave. A Mexican wave is a large scale example of a metachronal wave. This pattern is found widely in nature such as on the cilia of many aquatic organisms such as ctenophores, molluscs, ciliates as well as on the epithelial surfaces of many body organs. Individual cilia, when part of a metachronal wave being used for protist locomotion, individually beat in a pattern similar to the planar stroke of a flagellum. The difference is that the recovery stroke is at 90 degrees to the power stroke, so that the cilia avoid hitting each other. Metachronal rhythms may be seen in the coordinated movements of the legs of millipedes and other multi-legged land invertebrates, as well as in the coordinated movements of social insects. Such metachronal mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stroke (engine)
In the context of an internal combustion engine, the term stroke has the following related meanings: * A phase of the engine's cycle (e.g. compression stroke, exhaust stroke), during which the piston travels from top to bottom or vice versa. * The type of power cycle used by a piston engine (e.g. two-stroke engine, four-stroke engine). * "Stroke length", the distance travelled by the piston during each cycle. The stroke length––along with bore diameter––determines the engine's displacement. Phases in the power cycle Commonly used engine phases or strokes (i.e. those used in a four-stroke engine) are described below. Other types of engines can have very different phases. Induction-intake stroke The induction stroke is the first phase in a four-stroke (e.g. Otto cycle or Diesel cycle) engine. It involves the downward movement of the piston, creating a partial vacuum that draws a air-fuel mixture (or air alone, in the case of a direct injection engine) into the combus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Locomotion
Animal locomotion, in ethology, is any of a variety of methods that animal (biology), animals use to move from one place to another. Some modes of locomotion are (initially) self-propelled, e.g., running, swimming, jumping, flying, hopping, soaring and gliding. There are also many animal species that depend on their environment for transportation, a type of mobility called Passive locomotion in animals, passive locomotion, e.g., sailing (some jellyfish), Ballooning (spider), kiting (spiders), rolling (some beetles and spiders) or riding other animals (phoresis (biology), phoresis). Animals move for a variety of reasons, such as to find Foraging, food, a Mating system, mate, a suitable microhabitat, or to Escape response, escape predators. For many animals, the ability to move is essential for survival and, as a result, natural selection has shaped the locomotion methods and mechanisms used by moving organisms. For example, Animal migration, migratory animals that travel vast dista ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metachronal Swimming
A metachronal swimming or metachronal rowing is the swimming technique used by animals with multiple pairs of swimming legs. In this technique, appendages are sequentially stroked in a back-to-front wave moving along the animal’s body. In literature, while metachronal rhythm or metachronal wave usually refer to the movement of cilia; metachronal coordination, metachronal beating, metachronal swimming or metachronal rowing usually refer to the leg movement of arthropods, such as mantis shrimp, copepods, antarctic krill etc. though all of them refer to the similar locomotion pattern. Metachronous indicates something not functioning or occurring synchronously, or occurring or starting at different times. This word is derived from Greek meta- μετά- meaning, occurring later than or in succession to : after, and -chronous -Χρόνος meaning, of (such) a time or period. Swimming legs should coordinate to avoid interference among appendage pairs. To accomplish this challenge, almo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phi Phenomenon
The term phi phenomenon is used in a narrow sense for an apparent motion that is observed if two nearby optical stimuli are presented in alternation with a relatively high frequency. In contrast to beta movement, seen at lower frequencies, the stimuli themselves do not appear to move. Instead, a diffuse, amorphous shadowlike something seems to jump in front of the stimuli and occlude them temporarily. This shadow seems to have nearly the color of the background. Max Wertheimer first described this form of apparent movement in his habilitation thesis, published 1912, marking the birth of Gestalt psychology. In a broader sense, particularly if the plural form ''phi phenomena'' is used, it applies also to all apparent movements that can be seen if two nearby optical stimuli are presented in alternation. This includes especially beta movement, which has been regarded as the illusion of motion in cinema and animation, although it can be argued that beta movement indicates long-range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Movement
The term Beta movement is used for the optical illusion of apparent motion in which the very short projection of one figure and a subsequent very short projection of a more or less similar figure in a different location are experienced as one figure that moves. The illusion of motion caused by animation and film is sometimes believed to rely on beta movement, as an alternative to the older explanation known as persistence of vision. However, there are notable differences between the short-range apparent motion that occurs in film (with little differences between successive images) and the long-range apparent motion originally described as beta movement (with bigger differences between positions of successive images). Examples of use The beta movement effect has been widely used in news ticker technology and is commonly seen in LED displays. History Observations of apparent motion through quick succession of images go back to the 19th century. In 1833, Joseph Plateau introd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mytilus Edulis
The blue mussel (''Mytilus edulis''), also known as the common mussel, is a medium-sized edible marine (ocean), marine bivalve mollusc in the family (biology), family Mytilidae, the mussels. Blue mussels are subject to commercial use and intensive aquaculture. A species with a large range, empty shells are commonly found on beaches around the world. Systematics and distribution The ''Mytilus edulis'' complex Systematically blue mussel consists of a group of (at least) three closely related taxa of mussels, known as the ''Mytilus edulis'' complex. Collectively they occupy both coasts of the North Atlantic (including the Mediterranean) and of the North Pacific in temperate to polar waters, as well as coasts of similar nature in the Southern Hemisphere. The distribution of the component taxa has been recently modified as a result of human activity. The taxa can hybridise with each other, if present at the same locality. *''Mytilus edulis'' sensu stricto: Native to the North Atla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Millipede
Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a result of two single segments fused together. Most millipedes have very elongated cylindrical or flattened bodies with more than 20 segments, while pill millipedes are shorter and can roll into a tight ball. Although the name "millipede" derives from the Latin for "thousand feet", no species was known to have 1,000 or more until the discovery of ''Eumillipes persephone'', which can have over 1,300 legs. There are approximately 12,000 named species classified into 16 orders and around 140 families, making Diplopoda the largest class of myriapods, an arthropod group which also includes centipedes and other multi-legged creatures. Most millipedes are slow-moving detritivores, eating decaying leaves and other dead plant matter. Some eat fungi or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellum
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have from one to many flagella. A gram-negative bacterium ''Helicobacter pylori'' for example uses its multiple flagella to propel itself through the mucus lining to reach the stomach epithelium, where it may cause a gastric ulcer to develop. In some bacteria the flagellum can also function as a sensory organelle, being sensitive to wetness outside the cell. Across the three domains of Bacteria, Archaea, and Eukaryota the flagellum has a different structure, protein composition, and mechanism of propulsion but shares the same function of providing motility. The Latin word means " whip" to describe its lash-like swimming motion. The flagellum in archaea is called the archaellum to note its difference from the bacterial flagellum. Eukaryotic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protist
A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exclusion of other eukaryotes means that protists do not form a natural group, or clade. Therefore, some protists may be more closely related to animals, plants, or fungi than they are to other protists. However, like the groups ''algae'', ''invertebrates'', and '' protozoans'', the biological category ''protist'' is used for convenience. Others classify any unicellular eukaryotic microorganism as a protist. The study of protists is termed protistology. History The classification of a third kingdom separate from animals and plants was first proposed by John Hogg in 1860 as the kingdom Protoctista; in 1866 Ernst Haeckel also proposed a third kingdom Protista as "the kingdom of primitive forms". Originally these also included prokaryotes, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of epithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
