Topic Review
μ-Recursive Function
In mathematical logic and computer science, the general recursive functions (often shortened to recursive functions) or μ-recursive functions are a class of partial functions from natural numbers to natural numbers that are "computable" in an intuitive sense. In computability theory, it is shown that the μ-recursive functions are precisely the functions that can be computed by Turing machines(this is one of the theorems that supports the Church–Turing thesis). The μ-recursive functions are closely related to primitive recursive functions, and their inductive definition (below) builds upon that of the primitive recursive functions. However, not every μ-recursive function is a primitive recursive function—the most famous example is the Ackermann function. Other equivalent classes of functions are the λ-recursive functions and the functions that can be computed by Markov algorithms. The subset of all total recursive functions with values in {0,1} is known in computational complexity theory as the complexity class R.
  • 5
  • 01 Dec 2022
Topic Review
β-Adrenergic Stimulation
β-adrenergic receptor stimulation (β-ARS) is a physiological mechanism that regulates cardiovascular function under stress conditions or physical exercise, producing a positive inotropic (enhanced contraction), lusitropic (faster relaxation), and chronotropic (increased heart rate) effect. 
  • 376
  • 04 Aug 2021
Topic Review
Zoom Meetings (commonly shortened to Zoom, and stylized as zoom) is a proprietary videotelephony software program developed by Zoom Video Communications. The free plan allows up to 100 concurrent participants, with a 40-minute time restriction. Users have the option to upgrade by subscribing to a paid plan. The highest plan supports up to 1,000 concurrent participants for meetings lasting up to 30 hours. During the COVID-19 pandemic, there was a major increase in the use of Zoom for remote work, distance education, and online social relations. The increase led to Zoom being one of the most downloaded mobile app worldwide in 2020 with over 500 million downloads. In 2020 Zoom had over 300 million daily meeting participants.
  • 48
  • 18 Oct 2022
Topic Review
Zone File
A Domain Name System (DNS) zone file is a text file that describes a DNS zone. A DNS zone is a subset, often a single domain, of the hierarchical domain name structure of the DNS. The zone file contains mappings between domain names and IP addresses and other resources, organized in the form of text representations of resource records (RR). A zone file may be either a DNS master file, authoritatively describing a zone, or it may be used to list the contents of a DNS cache.
  • 47
  • 13 Oct 2022
Topic Review
Zermelo's Theorem (Game Theory)
In game theory, Zermelo's theorem is a theorem about finite two-person games of perfect information in which the players move alternately and in which chance does not affect the decision making process. It says that if the game cannot end in a draw, then one of the two players must have a winning strategy (i.e. can force a win). An alternate statement is that for a game meeting all of these conditions except the condition that a draw is now possible, then either the first-player can force a win, or the second-player can force a win, or both players can force a draw. The theorem is named after Ernst Zermelo, a German mathematician and logician, who proved the theorem for the example game of chess in 1913.
  • 22
  • 15 Nov 2022
Topic Review
Zend Framework
Zend Framework (ZF) is an open source, object-oriented web application framework implemented in PHP 7 and licensed under the New BSD License. The framework is basically a collection of professional PHP-based packages. The framework uses various packages by the use of Composer as part of its package dependency managers; some of them are PHPUnit for testing all packages, Travis CI for continuous Integration Services. Zend Framework provides to users a support of the Model View Controller (MVC) in combination with Front Controller solution. MVC implementation in Zend Framework has five main areas. The router and dispatcher functions to decide which controller to run based on data from URL, and controller functions in combination with the model and view to develop and create the final web page. On 17 April 2019 it was announced that the framework is transitioning into an open source project hosted by the Linux Foundation to be known as Laminas.
  • 75
  • 01 Nov 2022
Topic Review
Z4 (Computer)
The Z4 was arguably the world's first commercial digital computer. It was designed, and manufactured by early computer scientist Konrad Zuse's company Zuse Apparatebau, for an order placed by Henschel & Son, in 1942; though only partially assembled in Berlin, then completed in Göttingen, and not delivered by the defeat of Nazi Germany, in 1945. The Z4 was Zuse's final target for the Z3 design. Like the earlier Z2, it comprised a combination of mechanical memory and electromechanical logic, so was not a true electronic computer.
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  • 08 Nov 2022
Topic Review
Yuktibhāṣā (Malayalam: യുക്തിഭാഷ, lit. 'Rationale'), also known as Gaṇita-yukti-bhāṣā:xxi and Gaṇitanyāyasaṅgraha (Compendium of Astronomical Rationale), is a major treatise on mathematics and astronomy, written by the India n astronomer Jyesthadeva of the Kerala school of mathematics around 1530. The treatise, written in Malayalam, is a consolidation of the discoveries by Madhava of Sangamagrama, Nilakantha Somayaji, Parameshvara, Jyeshtadeva, Achyuta Pisharati, and other astronomer-mathematicians of the Kerala school. It also exists in a Sanskrit version, with unclear author and date, composed as a rough translation of the Malayalam original. The work contains proofs and derivations of the theorems that it presents. Modern historians used to assert, based on the works of Indian mathematics that first became available, that early Indian scholars in astronomy and computation lacked in proofs, but Yuktibhāṣā demonstrates otherwise. Some of its important topics include the infinite series expansions of functions; power series, including of π and π/4; trigonometric series of sine, cosine, and arctangent; Taylor series, including second and third order approximations of sine and cosine; radii, diameters and circumferences; and tests of convergence. Yuktibhāṣā mainly gives rationale for the results in Nilakantha's Tantra Samgraha. It is considered an early text on the ideas of calculus, predating Newton and Leibniz by centuries. The treatise was largely unnoticed outside India, as it was written in the local language of Malayalam. In modern times, due to wider international cooperation in mathematics, the wider world has taken notice of the work. For example, both Oxford University and the Royal Society of Great Britain have given attribution to pioneering mathematical theorems of Indian origin that predate their Western counterparts.
  • 9
  • 21 Nov 2022
Topic Review
Attention Mechanism-Based Lightweight YOLOv5 for Track Pedestrian Detection. In response to the dangerous behavior of pedestrians roaming freely on unsupervised train tracks, the real-time detection of pedestrians is urgently required to ensure the safety of trains and people. Aiming to improve the low accuracy of railway pedestrian detection, the high missed-detection rate of target pedestrians, and the poor retention of non-redundant boxes, YOLOv5 is adopted as the baseline to improve the effectiveness of pedestrian detection by model pruning, improving attention mechanism, etc.
  • 188
  • 15 Sep 2022
Topic Review
Yarovaya Law
The Yarovaya law (in Russian: Закон Яровой, transliteration: Zakon Jarovoy), also Yarovaya package/bag, is a set of two Russia n federal bills, 374-FZ and 375-FZ, passed in 2016. The bills amend previous counter-terrorism law and separate laws regulating additional counter-terror and public safety measures. It is known to the public under the last name of one of its creators—Irina Yarovaya. The amendments included an expansion of authority for law enforcement agencies, new requirements for data collection and mandatory decoding in the telecommunications industry, as well as the increased regulation of evangelism, including a ban on the performance of "missionary activities" in non-religious settings.
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  • 12 Oct 2022
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