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43-436: The space harp , also known as a frankiphone , is an electrified lamellophone invented by Phil Cohran as part of a musicological experiment exploring his African roots. He named it after his mother, Frankie. It was first recorded during his tenure with Sun Ra on his album " Angels and Demons at Play ". Later recordings of the space harp include his work in the 1960s with The Artistic Heritage Ensemble , now available on

86-470: A case where the "feed-back" action is positive in contrast to negative feed-back action, which they mentioned only in passing. Harold Stephen Black 's classic 1934 paper first details the use of negative feedback in electronic amplifiers. According to Black: Positive feed-back increases the gain of the amplifier, negative feed-back reduces it. According to Mindell (2002) confusion in the terms arose shortly after this: ...   Friis and Jensen had made

129-493: A circular argument. This makes reasoning based upon cause and effect tricky, and it is necessary to analyze the system as a whole. As provided by Webster, feedback in business is the transmission of evaluative or corrective information about an action, event, or process to the original or controlling source. Self-regulating mechanisms have existed since antiquity, and the idea of feedback started to enter economic theory in Britain by

172-482: A classic in feedback control theory. This was a landmark paper on control theory and the mathematics of feedback. The verb phrase to feed back , in the sense of returning to an earlier position in a mechanical process, was in use in the US by the 1860s, and in 1909, Nobel laureate Karl Ferdinand Braun used the term "feed-back" as a noun to refer to (undesired) coupling between components of an electronic circuit . By

215-434: A deliberate effect via some more tangible connection. [Practical experimenters] object to the mathematician's definition, pointing out that this would force them to say that feedback was present in the ordinary pendulum ... between its position and its momentum—a "feedback" that, from the practical point of view, is somewhat mystical. To this the mathematician retorts that if feedback is to be considered present only when there

258-1841: A frame or hoop 121.1 Clack idiophones or Cricri - The lamella is carved in the surface of a fruit shell, which serves as resonator. Also known as galip nut snapper. 121.2 Guimbardes and jaw harps - The lamella is mounted in a rod- or plaque-shaped frame and depends on the player's mouth cavity for resonance. The lamellae are tied to a board or cut out from a board like the teeth of a comb. 122.1 With laced on lamellae. 122.11 Without resonator. 122.12 With resonator. 122.2 With cut-out lamellae Feedback Collective intelligence Collective action Self-organized criticality Herd mentality Phase transition Agent-based modelling Synchronization Ant colony optimization Particle swarm optimization Swarm behaviour Social network analysis Small-world networks Centrality Motifs Graph theory Scaling Robustness Systems biology Dynamic networks Evolutionary computation Genetic algorithms Genetic programming Artificial life Machine learning Evolutionary developmental biology Artificial intelligence Evolutionary robotics Reaction–diffusion systems Partial differential equations Dissipative structures Percolation Cellular automata Spatial ecology Self-replication Conversation theory Entropy Feedback Goal-oriented Homeostasis Information theory Operationalization Second-order cybernetics Self-reference System dynamics Systems science Systems thinking Sensemaking Variety Ordinary differential equations Phase space Attractors Population dynamics Chaos Multistability Bifurcation Rational choice theory Bounded rationality Feedback occurs when outputs of

301-419: A nutrient elicits changes in some of their metabolic functions. Feedback is also central to the operations of genes and gene regulatory networks . Repressor (see Lac repressor ) and activator proteins are used to create genetic operons , which were identified by François Jacob and Jacques Monod in 1961 as feedback loops . These feedback loops may be positive (as in the case of the coupling between

344-582: A process, whereas the positive feedback loop tends to accelerate it. The mirror neurons are part of a social feedback system, when an observed action is "mirrored" by the brain—like a self-performed action. Normal tissue integrity is preserved by feedback interactions between diverse cell types mediated by adhesion molecules and secreted molecules that act as mediators; failure of key feedback mechanisms in cancer disrupts tissue function. In an injured or infected tissue, inflammatory mediators elicit feedback responses in cells, which alter gene expression, and change

387-403: A role in southeast African Music . They were reported as early as the 16th century, but there is no doubt they have a much longer history. The Caribbean marímbula is also of this family. The marímbula can be seen as a bass variant of the mbira and is sometimes used in hip hop music . In most cases the tongues are divided in two playing halves with the lowest notes in the centre; from there to

430-619: A similar tradition and Yuri Landman has made 12-TET bass kalimbas and metal tongue drums . Schaeffner's musical instrument classification scheme has a post-prominent place for the linguaphones (lamellophones) at the second highest level of classification. In 1932, Andre Schaeffner developed a new classification scheme that was "exhaustive, potentially covering all real and conceivable instruments" [Kartomi, p. 176]. Schaeffner's system has only two top-level categories denoted by Roman numerals (Schaeffner, A.: Origine des instruments de musique , pp. 371–377.): The lamellae vibrate within

473-524: A single discipline an example of feedback can be called either positive or negative, depending on how values are measured or referenced. This confusion may arise because feedback can be used to provide information or motivate , and often has both a qualitative and a quantitative component. As Connellan and Zemke (1993) put it: Quantitative feedback tells us how much and how many. Qualitative feedback tells us how good, bad or indifferent. While simple systems can sometimes be described as one or

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516-481: A sugar molecule and the proteins that import sugar into a bacterial cell), or negative (as is often the case in metabolic consumption). On a larger scale, feedback can have a stabilizing effect on animal populations even when profoundly affected by external changes, although time lags in feedback response can give rise to predator-prey cycles . In zymology , feedback serves as regulation of activity of an enzyme by its direct product(s) or downstream metabolite(s) in

559-418: A system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to feed back into itself. The notion of cause-and-effect has to be handled carefully when applied to feedback systems: Simple causal reasoning about a feedback system is difficult because the first system influences the second and second system influences the first, leading to

602-430: Is a lamellophone with an alternate tine configuration. It is electrified by the addition of a 2-channel stereo piezo cable pickup system. A special solid-body Array mbira exists. Ernst Zacharias created a series of electric lamellophones created in the 1960s for Hohner . These instruments were based on the reeds made by Hohner (already employed in accordions, concertinas, melodicas and harmonicas). These instruments were

645-399: Is also found in certain behaviour. For example, "shame loops" occur in people who blush easily. When they realize that they are blushing, they become even more embarrassed, which leads to further blushing, and so on. The climate system is characterized by strong positive and negative feedback loops between processes that affect the state of the atmosphere, ocean, and land. A simple example is

688-461: Is an actual wire or nerve to represent it, then the theory becomes chaotic and riddled with irrelevancies. Focusing on uses in management theory, Ramaprasad (1983) defines feedback generally as "...information about the gap between the actual level and the reference level of a system parameter" that is used to "alter the gap in some way". He emphasizes that the information by itself is not feedback unless translated into action. Positive feedback: If

731-453: Is the car; its input includes the combined torque from the engine and from the changing slope of the road (the disturbance). The car's speed (status) is measured by a speedometer . The error signal is the difference of the speed as measured by the speedometer from the target speed (set point). The controller interprets the speed to adjust the accelerator, commanding the fuel flow to the engine (the effector). The resulting change in engine torque,

774-512: Is used to boost poor performance (narrow a gap). Referring to definition 1, some authors use alternative terms, replacing positive and negative with self-reinforcing and self-correcting , reinforcing and balancing , discrepancy-enhancing and discrepancy-reducing or regenerative and degenerative respectively. And for definition 2, some authors promote describing the action or effect as positive and negative reinforcement or punishment rather than feedback. Yet even within

817-703: The Hornbostel–Sachs system for classifying musical instruments, plucked idiophones . There are two main categories of plucked idiophones, those that are in the form of a frame (121) and those that are in the form of a comb (122). According to Sachs , The most usual [of plucked idiophones] is a flexible lamella or tongue attached to a frame, plucked by a finger and resonated by a small box. A large number of lamellophones originate in Africa , where they are known under different names including mbira , kisanji , likembe , kalimba , kongoma , and sanza . They play

860-895: The Pianet (plucked by a foam pad), the Cembalet (plucked by a rubber pad) and the Guitaret (plucked by fingers). The idea of a struck reed tongue had been pioneered by the Alexandre brothers in their "Orgues expressifs" ( harmoniums ) in the 19th century, where they were called percussion stops. The Space Harp , or Frankiphone (designed, built and played by Phil Cohran ), is a famous instance of an electric lamellophone. A range of other mbiras and kalimbas have been created by contemporary instrument makers. The African band Konono No.1 uses custom-built electric kalimbas with electro-magnetic pickups. Neptune 's Jason Sanford makes electric thumb pianos from scrap in

903-417: The biosphere , most parameters must stay under control within a narrow range around a certain optimal level under certain environmental conditions. The deviation of the optimal value of the controlled parameter can result from the changes in internal and external environments. A change of some of the environmental conditions may also require change of that range to change for the system to function. The value of

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946-403: The centrifugal governors used in steam engines. He distinguished those that lead to a continued increase in a disturbance or the amplitude of a wave or oscillation, from those that lead to a decrease of the same quality. The terms positive and negative feedback are defined in different ways within different disciplines. The two definitions may be confusing, like when an incentive (reward)

989-402: The indigenous peoples of Siberia play wooden and metallic lamellophones with a single tongue. Lamellophones may be made with or without resonators . There are also electric lamellophones with an additional pickup . Electric lamellophones have been electrified with an electro-magnetic pickup (like on electric guitars) or contact piezo pickup . There is a distinct difference between

1032-401: The steam engines of their production. Early steam engines employed a purely reciprocating motion , and were used for pumping water – an application that could tolerate variations in the working speed, but the use of steam engines for other applications called for more precise control of the speed. In 1868 , James Clerk Maxwell wrote a famous paper, "On governors", that is widely considered

1075-455: The 18th century, but it was not at that time recognized as a universal abstraction and so did not have a name. The first ever known artificial feedback device was a float valve , for maintaining water at a constant level, invented in 270 BC in Alexandria , Egypt . This device illustrated the principle of feedback: a low water level opens the valve, the rising water then provides feedback into

1118-445: The 1940s onwards was centred around the study of circular causal feedback mechanisms. Over the years there has been some dispute as to the best definition of feedback. According to cybernetician Ashby (1956), mathematicians and theorists interested in the principles of feedback mechanisms prefer the definition of "circularity of action", which keeps the theory simple and consistent. For those with more practical aims, feedback should be

1161-465: The album entitled On the Beach . This album consists of recordings of The Artistic Heritage Ensemble , which included a number of well known musicians including Don Myrick (horn player with Earth, Wind and Fire ), Pete Cosey (guitarist with Miles Davis ) and "Master" Henry Gibson (studio percussionist for Motown ). Released in 2007, the entire album revolves around the rhythmic and harmonic stylings of

1204-443: The current state and inputs are used to calculate a new state which is then fed back and clocked back into the device to update it. By using feedback properties, the behavior of a system can be altered to meet the needs of an application; systems can be made stable, responsive or held constant. It is shown that dynamical systems with a feedback experience an adaptation to the edge of chaos . Physical systems present feedback through

1247-450: The end of 1912, researchers using early electronic amplifiers ( audions ) had discovered that deliberately coupling part of the output signal back to the input circuit would boost the amplification (through regeneration ), but would also cause the audion to howl or sing. This action of feeding back of the signal from output to input gave rise to the use of the term "feedback" as a distinct word by 1920. The development of cybernetics from

1290-405: The feedback, combines with the torque exerted by the change of road grade to reduce the error in speed, minimising the changing slope. The terms "positive" and "negative" were first applied to feedback prior to WWII. The idea of positive feedback already existed in the 1920s when the regenerative circuit was made. Friis and Jensen (1924) described this circuit in a set of electronic amplifiers as

1333-442: The groups of molecules expressed and secreted, including molecules that induce diverse cells to cooperate and restore tissue structure and function. This type of feedback is important because it enables coordination of immune responses and recovery from infections and injuries. During cancer, key elements of this feedback fail. This disrupts tissue function and immunity. Mechanisms of feedback were first elucidated in bacteria, where

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1376-617: The left and to the right each tongue is tuned higher than the previous one. The tongues may also be arranged in a linear arrangement in the manner of a piano . Tongues may be made small enough to play with individual fingers, hence the colloquial name "thumb piano". (Although some instruments, like the Mbira , have an additional rows of tongues, in which case not just the thumbs are used for plucking.) Some conjecture that African lamellophones were derived from xylophones and marimbas . However, similar instruments have been found elsewhere; for example,

1419-426: The metabolic pathway (see Allosteric regulation ). The hypothalamic–pituitary–adrenal axis is largely controlled by positive and negative feedback, much of which is still unknown. In psychology , the body receives a stimulus from the environment or internally that causes the release of hormones . Release of hormones then may cause more of those hormones to be released, causing a positive feedback loop. This cycle

1462-455: The mutual interactions of its parts. Feedback is also relevant for the regulation of experimental conditions, noise reduction, and signal control. The thermodynamics of feedback-controlled systems has intrigued physicist since the Maxwell's demon , with recent advances on the consequences for entropy reduction and performance increase. In biological systems such as organisms , ecosystems , or

1505-470: The other type, many systems with feedback loops cannot be shoehorned into either type, and this is especially true when multiple loops are present. When there are only two parts joined so that each affects the other, the properties of the feedback give important and useful information about the properties of the whole. But when the parts rise to even as few as four, if every one affects the other three, then twenty circuits can be traced through them; and knowing

1548-415: The output of one affecting the input of another, and vice versa. Some systems with feedback can have very complex behaviors such as chaotic behaviors in non-linear systems, while others have much more predictable behaviors, such as those that are used to make and design digital systems. Feedback is used extensively in digital systems. For example, binary counters and similar devices employ feedback where

1591-428: The parameter to maintain is recorded by a reception system and conveyed to a regulation module via an information channel. An example of this is insulin oscillations . Biological systems contain many types of regulatory circuits, both positive and negative. As in other contexts, positive and negative do not imply that the feedback causes good or bad effects. A negative feedback loop is one that tends to slow down

1634-489: The piezo and the electro-magnetic pickup. Most electric lamellophones feature piezo pickups. The piezo sound contains more treble and has more problems with feedback when amplified ( distorted ) heavily. Lucinda Ellison produces a wide range of her Embiras, which are solid body electric mbiras with piezo pickups — a design first conceived in 1981 and finalised in 1996. David Bellinger has been making ekalimbas - kalimbas with piezo pickups - for 20 years. The Array Mbira

1677-502: The properties of all the twenty circuits does not give complete information about the system. In general, feedback systems can have many signals fed back and the feedback loop frequently contain mixtures of positive and negative feedback where positive and negative feedback can dominate at different frequencies or different points in the state space of a system. The term bipolar feedback has been coined to refer to biological systems where positive and negative feedback systems can interact,

1720-598: The same distinction Black used between "positive feed-back" and "negative feed-back", based not on the sign of the feedback itself but rather on its effect on the amplifier's gain. In contrast, Nyquist and Bode, when they built on Black's work, referred to negative feedback as that with the sign reversed. Black had trouble convincing others of the utility of his invention in part because confusion existed over basic matters of definition. Even before these terms were being used, James Clerk Maxwell had described their concept through several kinds of "component motions" associated with

1763-428: The signal feedback from output is in phase with the input signal, the feedback is called positive feedback. Negative feedback: If the signal feedback is out of phase by 180° with respect to the input signal, the feedback is called negative feedback. As an example of negative feedback, the diagram might represent a cruise control system in a car that matches a target speed such as the speed limit. The controlled system

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1806-604: The space harp. This article relating to lamellophones is a stub . You can help Misplaced Pages by expanding it . Electric lamellophones Linguaphone comes from the Latin root lingua meaning "tongue", (i.e., a long thin plate that is fixed only at one end). lamellophone comes from the Latin word lamella for "small metal plate", and the Greek word φωνή phonē for "sound, voice". The lamellophones constitute category 12 in

1849-413: The system, closing the valve when the required level is reached. This then reoccurs in a circular fashion as the water level fluctuates. Centrifugal governors were used to regulate the distance and pressure between millstones in windmills since the 17th century. In 1788, James Watt designed his first centrifugal governor following a suggestion from his business partner Matthew Boulton , for use in

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