A Turing machine is a mathematical model of computation that defines an abstract machine, which manipulates symbols on a strip of tape according to a table of rules. Despite the model's simplicity, given any computer algorithm, a Turing machine capable of simulating that algorithm's logic can be constructed; the machine operates on an infinite memory tape divided into discrete "cells". The machine positions its "head" over a cell and "reads" or "scans" the symbol there; as per the symbol and its present place in a "finite table" of user-specified instructions, the machine writes a symbol in the cell either moves the tape one cell left or right either proceeds to a subsequent instruction or halts the computation. The Turing machine was invented in 1936 by Alan Turing, who called it an "a-machine". With this model, Turing was able to answer two questions in the negative: does a machine exist that can determine whether any arbitrary machine on its tape is "circular", thus by providing a mathematical description of a simple device capable of arbitrary computations, he was able to prove properties of computation in general—and in particular, the uncomputability of the Entscheidungsproblem.
Thus, Turing machines prove fundamental limitations on the power of mechanical computation. While they can express arbitrary computations, their minimalist design makes them unsuitable for computation in practice: real-world computers are based on different designs that, unlike Turing machines, use random-access memory. Turing completeness is the ability for a system of instructions to simulate a Turing machine. A programming language, Turing complete is theoretically capable of expressing all tasks accomplishable by computers. A Turing machine is a general example of a central processing unit that controls all data manipulation done by a computer, with the canonical machine using sequential memory to store data. More it is a machine capable of enumerating some arbitrary subset of valid strings of an alphabet. A Turing machine has a tape of infinite length on which it can perform write operations. Assuming a black box, the Turing machine cannot know whether it will enumerate any one specific string of the subset with a given program.
This is due to the fact that the halting problem is unsolvable, which has major implications for the theoretical limits of computing. The Turing machine is capable of processing an unrestricted grammar, which further implies that it is capable of robustly evaluating first-order logic in an infinite number of ways; this is famously demonstrated through lambda calculus. A Turing machine, able to simulate any other Turing machine is called a universal Turing machine. A more mathematically oriented definition with a similar "universal" nature was introduced by Alonzo Church, whose work on lambda calculus intertwined with Turing's in a formal theory of computation known as the Church–Turing thesis; the thesis states that Turing machines indeed capture the informal notion of effective methods in logic and mathematics, provide a precise definition of an algorithm or "mechanical procedure". Studying their abstract properties yields many insights into computer science and complexity theory. In his 1948 essay, "Intelligent Machinery", Turing wrote that his machine consisted of:...an unlimited memory capacity obtained in the form of an infinite tape marked out into squares, on each of which a symbol could be printed.
At any moment there is one symbol in the machine. The machine can alter the scanned symbol, its behavior is in part determined by that symbol, but the symbols on the tape elsewhere do not affect the behavior of the machine. However, the tape can be moved back and forth through the machine, this being one of the elementary operations of the machine. Any symbol on the tape may therefore have an innings; the Turing machine mathematically models a machine. On this tape are symbols, which the machine can read and write, one at a time, using a tape head. Operation is determined by a finite set of elementary instructions such as "in state 42, if the symbol seen is 0, write a 1. In the original article, Turing imagines not a mechanism, but a person whom he calls the "computer", who executes these deterministic mechanical rules slavishly. A Turing machine consists of: A tape divided into cells, one next to the other; each cell contains a symbol from some finite alphabet. The alphabet contains one or more other symbols.
The tape is assumed to be arbitrarily extendable to the left and to the right, so that the Turing machine is always supplied with as much tape as it needs for its computation. Cells that have not been written before are assumed to be filled with the blank symbol. In some models the tape has a
Shakedown 3 is a compilation album by Freemasons. It was released on September 4, 2014; as with Freemasons' previous full-length release, Shakedown 2, Shakedown 3 features singles released since by the producing team, as well as some remixes for major artists, like Whitney Houston, Hurts, or John Newman. Small and Wiltshire decided to revive the Pegasus alias, which they used for a song of the same name. Multiple tracks from this project are thus showcased along the other tracks from the compilation; the physical release of Shakedown 3 consists of three CDs: the first two are mixes, the third one contains unmixed tracks, similar to their 2007 album Unmixed. A separate digital release, Shakedown 3, was released on November 30, it includes "DJ tools" tracks of songs from the album. All tracks are written except where noted. Notes "Discopolis" contains sections from "Tears" by Freemasons feat. Katherine Ellis. Production / Remix and additional production on all tracks by Freemasons, except "Gorecki": produced by Freemasons and Sarah De Courcy.
"Gorecki" is a cover of the song of the same name by the English electronic music duo Lamb. "La Serenissima" is a composition from La Serenissima, a 1981 album by Italian chamber orchestra Rondò Veneziano. "Intoxicated" contains lyrics lifted from Mariah Carey's 1991 single "Emotions". "Discopolis" is a cover of the track of the same name by Lifelike and Kris Menace
Natasha J. Cabrera is a Canadian developmental psychologist known for her research on children's cognitive and social development, focusing on fathers' involvement and influence on child development and cultural variations in parenting behaviors, factors associated with developmental risk, she holds the position of Professor in the Department of Human Development and Quantitative Methods at the University of Maryland, College of Education, where she is Director of the Family Involvement Laboratory and affiliated with the Maryland Population Research Center. Cabrera holds the position of Secretary on the Governing Council of the Society for the Research on Child Development and has served as Associate Editor of Early Childhood Research Quarterly and Child Development, her research has been featured in The Wall Street Journal, Education Week and The Atlantic. Cabrera is co-editor of several books, including From welfare to child care: What happens to young children when single mothers exchange welfare for work, Handbook of U.
S. Latino Psychology: Developmental and community-based perspectives,Latina and Latino Child Psychology and Mental Health, Handbook of Father Involvement: Multidisciplinary Perspectives. Cabrera graduated from the University of Toronto with BS degree in psychology in 1985 and MS degree in Philosophy of Education in 1989, she attended graduate school at the University of Denver, School of Education, where she obtained her Ph. D. in Educational and Developmental Psychology in 1994. After graduation, Cabrera worked as Study Director for the Roundtable on Head Start Research, Commission on Behavioral and Social Sciences and Education, Board on Children and Families National Research Council of the National Academy of Sciences from 1995-1996, she held the position of Executive Branch Fellow, sponsored by the Society for Research on Child Development under the auspices of the American Association for the Advancement of Science at the National Institute of Child Health and Human Development from 1996-1998.
Cabrera worked at the NICHD as an Expert in Child Development before joining the faculty of the University of Maryland in 2002. While at NICHD, Cabrera received the On-the-Spot Award, Individual Merit Award and Staff Recognition Award in 1997, 1999, 2000, the Administration for Children and Families, United States Department of Health and Human Service Secretary’s Distinguished Service Award and Fatherhood Leadership Award in 2000 and 2003. Cabrera's research on the influence of fathers in children's development has been supported by grants from the National Institutes of Health. Cabrera is known for her work addressing how fathers' involvement impacts children's development—a topic that has received less research attention than mothers' participation in children's lives. By focusing on fathers' involvement in relation to family and child outcomes, her research furthers understanding of parenting behaviors that impact children's cognitive and emotional well-being. Cabrera started her research by investigating the effects of fathers' involvement in the lives of children and families on existing social policies, such as child support and others.
By examining how modern social trends are changing fathers' contributions to child development, her research team has proposed several social programs and initiatives. As the next step in her work, Cabrera paid particular attention to an underrepresented group of ethnically diverse low-income families. In her studies, she argued that positive father-child interactions appeared to obviate potential cognitive delays associated with poverty, she claimed that fathers' socio-economic characteristics were uniquely associated with child developmental outcomes and highlighted how fathers' contributions in childcare should not be ignored. Cabrera's work provides empirical evidence for the significant effect of father engagement on cognitive, emotional and language development of children, she has argued that the quality of fathers' child-directed speech has a substantial contribution to children's receptive and expressive vocabulary skills. In addition, she has concluded that father-child relationship quality has the direct impact on children's peer-relationships and behavioral problems.
Her co-authored article Explaining the long reach of fathers’ prenatal involvement on paternal engagement with children was named Best Research Article regarding men in families by the National Council and Family Relations in 2009. In this article, Cabrera's team outlined important findings that unmarried fathers’ prenatal involvement was associated with their levels of paternal engagement when their child was one and three years of age. In another paper Fathers Are Parents, Too! Widening the Lens on Parenting for Children's Development and her colleagues provided a summary of the direct and indirect impact of fathers' involvement on child development. In this article, the authors discussed several issues related to father-child interaction and presented recommendations that can help further research to advance understanding of the role of fathering in a child's life. Cabrera, N. Fagan, J. & Farrie, D.. Explaining the long reach of fathers’ prenatal involvement on paternal engagement with children.
Journal of Marriage and the Family. 70, 1094-1107. Cabrera, N. Fitzgerald, H. E. Bradley, R. H. & Roggman, L.. Modeling the dynamics of paternal influences on children over the life course. Applied Development Science, 11, 185-189. Cabrera, N. Fitzgerald, H. Bradley, R. & Roggman, L.. The ecology of father-child relationships: An expanded model. Journal of Family Theory and Review, 6, 336-354. Cabrera N. J, Hofferth, S. & Hancock, G.. Family structure, maternal employment, change in children’s externalizing proble