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Signal-detection Theory
Detection theory or signal detection theory is a means to measure the ability to differentiate between information-bearing patterns (called stimulus in living organisms, signal in machines) and random patterns that distract from the information (called noise, consisting of background stimuli and random activity of the detection machine and of the nervous system of the operator). In the field of electronics, signal recovery is the separation of such patterns from a disguising background. According to the theory, there are a number of determiners of how a detecting system will detect a signal, and where its threshold levels will be. The theory can explain how changing the threshold will affect the ability to discern, often exposing how adapted the system is to the task, purpose or goal at which it is aimed. When the detecting system is a human being, characteristics such as experience, expectations, physiological state (e.g., fatigue) and other factors can affect the threshold app ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stimulus (psychology)
In psychology Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries betwe ..., a stimulus is any object or event that elicits a sensory or behavioral response in an organism. In this context, a distinction is made between the ''distal stimulus'' (the external, perceived object) and the ''proximal stimulus'' (the stimulation of sensory organs). *In perceptual psychology, a stimulus is an energy change (e.g., light or sound) which is registered by the senses (e.g., vision, hearing, taste, etc.) and constitutes the basis for perception. *In behavioral psychology (i.e., classical conditioning, classical and operant conditioning, operant conditioning), a stimulus constitutes the basis for behavior. The stimulus–response model emphasizes the relation between stimulus and behavior rather than an anim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyewitness Identification
In eyewitness identification, in criminal law, evidence is received from a witness "who has actually seen an event and can so testify in court". The Innocence Project states that "Eyewitness misidentification is the single greatest cause of wrongful convictions nationwide, playing a role in more than 75% of convictions overturned through DNA testing." This non-profit organization uses DNA evidence to reopen criminal convictions that were made before DNA testing was available as a tool in criminal investigations. Even before DNA testing revealed wrongful convictions based on eyewitness identifications, courts recognized and discussed the limits of eyewitness testimony. The late U.S. Supreme Court Justice William J. Brennan, Jr. observed in 1980 that "At least since ''United States v. Wade'', 388 U.S. 218 (1967), the Court has recognized the inherently suspect qualities of eyewitness identification evidence, and described the evidence as "notoriously unreliable", while noting tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nullspace Property
In compressed sensing, the Kernel (linear algebra), nullspace property gives necessary and sufficient conditions on the reconstruction of sparse signals using the techniques of Relaxation (approximation), \ell_1-relaxation. The term "nullspace property" originates from Cohen, Dahmen, and DeVore. The nullspace property is often difficult to check in practice, and the restricted isometry property is a more modern condition in the field of compressed sensing. The technique of Relaxation (approximation), \ell_1-relaxation The Convex optimization, non-convex \ell_0-minimization problem, \min\limits_ \, x\, _0 subject to Ax = b, is a standard problem in compressed sensing. However, \ell_0-minimization is known to be NP-hardness, NP-hard in general. As such, the technique of Relaxation (approximation), \ell_1-relaxation is sometimes employed to circumvent the difficulties of signal reconstruction using the \ell_0-norm. In Relaxation (approximation), \ell_1-relaxation, the Relaxation (a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Restricted Isometry Property
In linear algebra, the restricted isometry property (RIP) characterizes matrices which are nearly orthonormal, at least when operating on sparse vectors. The concept was introduced by Emmanuel Candès and Terence TaoE. J. Candes and T. Tao, "Decoding by Linear Programming," IEEE Trans. Inf. Th., 51(12): 4203–4215 (2005). and is used to prove many theorems in the field of compressed sensing. There are no known large matrices with bounded restricted isometry constants (computing these constants is strongly NP-hard, and is hard to approximate as well), but many random matrices have been shown to remain bounded. In particular, it has been shown that with exponentially high probability, random Gaussian, Bernoulli, and partial Fourier matrices satisfy the RIP with number of measurements nearly linear in the sparsity level. The current smallest upper bounds for any large rectangular matrices are for those of Gaussian matrices. Web forms to evaluate bounds for the Gaussian ensemble ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1708
In the Swedish calendar it was a leap year starting on Wednesday, one day ahead of the Julian and ten days behind the Gregorian calendar. Events January–June * January 1 – Charles XII of Sweden invades Russia, by crossing the frozen Vistula River with 40,000 men. * January 12 – Shahu I becomes the fifth Chhatrapati of the Maratha Empire in the Indian subcontinent. * February 26 – HMS ''Falmouth'', a 50-gun fourth-rate ship of the line built at Woolwich Dockyard for the Royal Navy, is launched. * March 11 – Queen Anne withholds Royal Assent from the Scottish Militia Bill, the last time a British monarch vetoes legislation. * March 23 – James Francis Edward Stuart, Jacobite pretender to the throne of Great Britain, unsuccessfully tries to land from a French fleet in the Firth of Forth in Scotland. * April 8 – Easter Sunday: The first performance of George Frideric Handel's oratorio ''La resurrezione'' takes place in Rome. * April ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
