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Topic Review
(ε, δ)-Definition of Limit
In calculus, the (ε, δ)-definition of limit ("epsilon–delta definition of limit") is a formalization of the notion of limit. The concept is due to Augustin-Louis Cauchy, who never gave a formal (ε, δ) definition of limit in his Cours d'Analyse, but occasionally used ε, δ arguments in proofs. It was first given as a formal definition by Bernard Bolzano in 1817, and the definitive modern statement was ultimately provided by Karl Weierstrass. It provides rigor to the following informal notion: the dependent expression f(x) approaches the value L as the variable x approaches the value c if f(x) can be made as close as desired to L by taking x sufficiently close to c.
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  • 22 Nov 2022
Topic Review
Nielsen Ratings
Nielsen TV ratings (commonly referred to as "Nielsen ratings") are the audience measurement systems operated by Nielsen Media Research that seek to determine the audience size and composition of television programming in the United States using a rating system. Nielsen Media Research was founded by Arthur C. Nielsen, a market analyst who started his career in the 1920s with marketing research and performance analysis. The company expanded into radio market analysis in the late 1930s, culminating in the Nielsen Radio Index in 1942, which was meant to provide statistics as to the markets of radio shows. The first Nielsen ratings for radio programs were released the first week of December 1947. They measured the top 20 programs in four areas: total audience, average audience, cumulative audience, and homes per dollar spent for time and talent. In 1950, Nielsen moved to television, developing a ratings system using the methods he and his company had developed for radio. That method became the primary source of audience measurement information in the US television industry.
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  • 29 Sep 2022
Topic Review
Solubility of Oxygen and Hydrogen in Water
Produced by photosynthesis, oxygen (O2) is a fundamentally important gas in biological systems, playing roles as a terminal electron receptor in respiration and in host defence through the creation of reactive oxygen species (ROS). Hydrogen (H2) plays a role in metabolism for some organisms, such as at thermal vents and in the gut environment, but has a role in controlling growth and development, and in disease states, both in plants and animals.
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  • 28 Feb 2024
Topic Review
The Perception of Achievement of Complex Thinking
The development of life competencies has become one of the primary objectives of contemporary universities. Beyond ensuring that students acquire knowledge, educational institutions are committed to developing professional skills that enable their graduates to know how to accomplish certain tasks, especially problem solving. One of these competencies, complex thinking, values people’s ability to reason when faced with challenging situations or problems. Globalization, daily use of technology, interactions in diverse environments, and the ever-increasing pressures of social movements mean that new professionals require a broader capacity for thinking than previous generations, which challenges universities to provide adequate training.
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  • 23 May 2022
Topic Review
Role-Playing Games
Role-Playing Games may be defined as a system for creating stories based on rules. They allow a group of players and a game director (also known as Game Master or Narrator) to participate and interact using their imagination to determine what could happen. There are different kinds of Role-Playing Games (RPGs) that relate to video games and online video games. The original RPGs, sometimes called tabletop RPGs or pen-and-paper RPGs, were the starting point of their digital relatives, and used mainly speech and imagination; however, technology may be used in some cases for communication. RPGs that are played by writing posts in forums or sending emails are called Play by Post (PbP). Some RPGs even require live interaction, similar to theater representations; these are called Live Action Role Play (LARP).
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  • 17 Dec 2021
Topic Review
Hot Dry Rock Geothermal Energy
Hot dry rock (HDR) is an extremely abundant source of geothermal energy that is difficult to access. A vast store of thermal energy is contained within hot – but essentially dry and impervious crystalline basement rocks found almost everywhere deep beneath Earth's surface. A concept for the extraction of useful amounts of geothermal energy from HDR originated at the Los Alamos National Laboratory in 1970, and Laboratory researchers were awarded a U.S. patent covering it. This technology has been tested extensively with multiple deep wells drilled in several field areas around world including the USA, Japan, Australia, France, and the UK and investment of billions of research funds. It continues to be the focus along with a related technique called EGS for sizable government-led research studies involving costly deep drilling and rock studies. Thermal energy has been recovered in reasonably sustainable tests over periods of years and in some cases electrical power generation was also achieved. However no commercial projects are ongoing or likely due to the high cost and limited capacity of the engineered reservoirs, associated wells, and pumping systems. Commonly tests have opened just one or more fractures such that the reservoir surface heat exchange areas are limited. For this technology to successfully compete with other energy sources, drilling costs would have to drop drastically or new approaches that result in much more extensive, complex, and higher rate flow paths through actual fracture networks would have to be established. The enthusiasim evident here on Wikipedia and in the research community is justified by the vast extent of the energy supply and the low environmental impact of the method however significant breakthroughs will be required to make this a commercial energy resource.
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  • 30 Oct 2022
Topic Review
Types of Insulation Materials
Insulation materials are classified into three main categories depending on material composition, material technology, and material sustainability index.
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  • 11 Jan 2023
Topic Review
Areas of Mathematics
Mathematics encompasses a growing variety and depth of subjects over its history, and comprehension of it requires a system to categorize and organize these various subjects into more general areas of mathematics. A number of different classification schemes have arisen, and though they share some similarities, there are differences due in part to the different purposes they serve. A traditional division of mathematics is into pure mathematics; mathematics studied for its intrinsic interest, and applied mathematics; the mathematics that can be directly applied to real-world problems. This division is not always clear and many subjects have been developed as pure mathematics to find unexpected applications later on. Broad divisions, such as discrete mathematics, computational mathematics and so on have emerged more recently. An ideal system of classification permits adding new areas into the organization of previous knowledge, and fitting surprising discoveries and unexpected interactions into the outline. For example, the Langlands program has found unexpected connections between areas previously thought unconnected, at least Galois groups, Riemann surfaces and number theory.
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  • 29 Sep 2022
Topic Review
Pathophysiology of Sepsis
Sepsis is a life-threatening condition characterized by an uncontrolled inflammatory response to an infectious agent and its antigens. Immune cell activation against the antigens causes severe distress that mediates a strong inflammatory response in vital organs. Sepsis is responsible for a high rate of morbidity and mortality in immunosuppressed patients. 
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  • 13 Mar 2023
Topic Review
Six-Gear Roadmap towards Smart Factory
The fourth industrial revolution is the transformation of manufacturing into smart manufacturing. Advanced industrial digital technologies that make the trend Industry 4.0 are considered as the transforming force that will enable this transformation. However, these technologies need to be connected, integrated and used effectively to create value and to provide insights for data driven manufacturing. Smart manufacturing is a journey and requires a roadmap to guide manufacturing organizations for its adoption. The proposed roadmap is a simple holistic management strategy for an Industry 4.0 implementation journey. It serves as a strategic practical tool for rapid adoption of Industry 4.0 technologies. It bridges the gap between the advanced technologies and their application in manufacturing industry, especially for SMEs.
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  • 06 Aug 2021
Biography
Fritz Haber
Fritz Haber (9 December 1868 – 29 January 1934) was a German[1] chemist who received the Nobel Prize in Chemistry in 1918 for his invention of the Haber–Bosch process, a method used in industry to synthesize ammonia from nitrogen gas and hydrogen gas. This invention is of importance for the large-scale synthesis of fertilizers and explosives. The food production for half the world's current
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  • 28 Nov 2022
Topic Review
Modular Construction
A modular construction is an assembly of standardized-dimension building elements such as wall panel, slab, beam or also an assembly of container-type units called “modules” or else “prefabricated prefinished volumetric construction (PPVC)” which are prefabricated in factory and afterwards transported and assembled on-site. The naming of “container house” is given to transportable modules that are completely finished in the factory and ready to be inhabited; for smaller units, eventually with different shapes, the nomenclature of “living pod” or “capsule” is also found in literature. Modular buildings are always prefabricated buildings, but the reverse is not necessarily true. The degree of prefabrication and assembly technique mainly varies depending on the life span of the building (temporary or permanent), the desired space layout and the technical equipment to install (heating, electricity, sewer, plumbing, etc.).
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  • 26 Oct 2020
Topic Review
Minkowski Diagram
The Minkowski diagram, also known as a spacetime diagram, was developed in 1908 by Hermann Minkowski and provides an illustration of the properties of space and time in the special theory of relativity. It allows a qualitative understanding of the corresponding phenomena like time dilation and length contraction without mathematical equations. Minkowski diagrams are two-dimensional graphs that depict events as happening in a universe consisting of one space dimension and one time dimension. Unlike a regular distance-time graph, the distance is displayed on the horizontal axis and time on the vertical axis. Additionally, the time and space units of measurement are chosen in such a way that an object moving at the speed of light is depicted as following a 45° angle to the diagram's axes. In this way, each object, like an observer or a vehicle, traces a certain line in the diagram, which is called its world line. Also, each point in the diagram represents a certain position in space and time, and is called an event, regardless of whether anything relevant happens there and then.
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  • 10 Oct 2022
Topic Review
Copper Heap Leaching
Heap leaching is a firm extractive metallurgical technology facilitating the economical processing of different kinds of low-grade ores that are otherwise not exploited.
  • 7.3K
  • 13 Oct 2021
Topic Review
Dhyāna in Buddhism
In the oldest texts of Buddhism, dhyāna (Sanskrit) or jhāna (Pāḷi) is the training of the mind, commonly translated as meditation, to withdraw the mind from the automatic responses to sense-impressions, and leading to a "state of perfect equanimity and awareness (upekkhā-sati-parisuddhi)." Dhyāna may have been the core practice of pre-sectarian Buddhism, in combination with several related practices which together lead to perfected mindfulness and detachment, and are fully realized with the practice of dhyana. In the later commentarial tradition, which has survived in present-day Theravāda, dhyāna is equated with "concentration," a state of one-pointed absorption in which there is a diminished awareness of the surroundings. In the contemporary Theravāda-based Vipassana movement, this absorbed state of mind is regarded as unnecessary and even non-beneficial for awakening, which has to be reached by mindfulness of the body and vipassanā (insight into impermanence). Since the 1980s, scholars and practitioners have started to question this equation, arguing for a more comprehensive and integrated understanding and approach, based on the oldest descriptions of dhyāna in the suttas. In Chán and Zen, the names of which Buddhist traditions are the Chinese and Japanese pronunciations, respectively, of dhyāna, dhyāna is the central practice, which is ultimately based on Sarvastivāda meditation practices, and has been transmitted since the beginning of the Common Era.
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  • 11 Oct 2022
Topic Review
Metallic Alloy Nanoparticles
Metallic alloy nanoparticles are synthesized by combining two or more different metals. Bimetallic or trimetallic nanoparticles are considered more effective than monometallic nanoparticles because of their synergistic characteristics. In this review, we outline the structure, synthesis method, properties, and biological applications of metallic alloy nanoparticles based on their plasmonic, catalytic, and magnetic characteristics.
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  • 03 Aug 2020
Topic Review
Country Code Top-Level Domain
A country code top-level domain (ccTLD) is an Internet top-level domain generally used or reserved for a country, sovereign state, or dependent territory identified with a country code. All ASCII ccTLD identifiers are two letters long, and all two-letter top-level domains are ccTLDs. In 2018, the Internet Assigned Numbers Authority (IANA) began implementing internationalized country code top-level domains, consisting of language-native characters when displayed in an end-user application. Creation and delegation of ccTLDs is described in RFC 1591, corresponding to ISO 3166-1 alpha-2 country codes. While gTLD have to obey international regulations, ccTLD are subjected to requirements that are determined by each country’s domain name regulation corporation. With over 150 million domain name registrations today, ccTLDs make up 40% of the total domain name industry. Country code extension applications began in 1985. The registered first extensions that year were .us (United States), .uk (United Kingdom), and .il (Israel). There are 312 ccTLDs in active use totally. .cn, .tk, .de and .uk contain the highest number of domains.
  • 7.3K
  • 08 Nov 2022
Biography
Mata Amritanandamayi
Mātā Amritānandamayī Devī (born Sudhamani Idamannel; 27 September 1953), often known simply as Amma ("Mother"), is an Indian Hindu spiritual leader, guru and humanitarian,[1][2] who is revered as 'the hugging saint' by her followers.[3] Mātā Amritānandamayī Devi is an Indian guru from Parayakadavu (now partially known as Amritapuri), Alappad Panchayat in Karunagappally, Kollam Distri
  • 7.3K
  • 16 Nov 2022
Topic Review
Conifers Phytochemicals
The phytochemical constituents present in conifer extracts are nontoxic at therapeutic levels, with polyphenolic compounds having significant biological activities. Stilbenes, terpenes, alkaloids, lignins and flavanoids, such as quercetin, rutin, resveratrol, and the compounds PYC and enzogenol, are the phytochemical components of conifer extracts reported to have sedative, antidiabetic, anticancer and anesthetic effects. In addition, phytochemicals present in conifer extracts assist in the regulation of glucose and lipid metabolism, insulin secretion, stimulating β cells, the NF-kB signaling pathway, the inhibition of gluconeogenic enzymes, ROS protective action as well as targeting and modulating cytokines which affect neuron cells and reduce oxidative stress.
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  • 01 Jun 2021
Topic Review
Xiaomi Redmi Note 4
The Xiaomi Redmi Note 4 is the fourth smartphone of Redmi Note series developed by Xiaomi Inc. It is a part of Xiaomi's budget Redmi smartphone line. It has two variants: The older version sold as Redmi Note 4 is powered by a Deca-core Mediatek MT6797 Helio X20 SOC. The upgraded version, sold both as Redmi Note 4X and Redmi Note 4 (where MTK version was not released) is powered by an Octa-core MSM8953 Qualcomm Snapdragon 625 SoC. The Redmi Note 4 was succeeded by Redmi Note 5.
  • 7.3K
  • 26 Oct 2022
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