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Topic Review
Holika
Holika (Sanskrit: होलिका) was a demoness in Hindu Vedic scriptures, who was burnt to death with the help of God Vishnu. She was the sister of King Hiranyakashipu and aunt of Prahlad. The story of Holika Dahan (Holika's death) signifies the triumph of good over evil. Holika is associated with the annual bonfire on the night before Holi, the Hindu festival of colors.
  • 3.2K
  • 29 Nov 2022
Topic Review
Solar Tree
A solar tree is a structure incorporating solar energy technology on a single pillar, like a tree trunk. It may be a solar artwork or a functional power generator.
  • 3.2K
  • 17 Oct 2022
Topic Review
Shear Strain
In physics, deformation is the continuum mechanics transformation of a body from a reference configuration to a current configuration. A configuration is a set containing the positions of all particles of the body. A deformation can occur because of external loads, intrinsic activity (e.g. muscle contraction), body forces (such as gravity or electromagnetic forces), or changes in temperature, moisture content, or chemical reactions, etc. Strain is related to deformation in terms of relative displacement of particles in the body that excludes rigid-body motions. Different equivalent choices may be made for the expression of a strain field depending on whether it is defined with respect to the initial or the final configuration of the body and on whether the metric tensor or its dual is considered. In a continuous body, a deformation field results from a stress field due to applied forces or because of some changes in the temperature field of the body. The relation between stress and strain is expressed by constitutive equations, e.g., Hooke's law for linear elastic materials. Deformations which cease to exist after the stress field is removed are termed as elastic deformation. In this case, the continuum completely recovers its original configuration. On the other hand, irreversible deformations remain. They exist even after stresses have been removed. One type of irreversible deformation is plastic deformation, which occurs in material bodies after stresses have attained a certain threshold value known as the elastic limit or yield stress, and are the result of slip, or dislocation mechanisms at the atomic level. Another type of irreversible deformation is viscous deformation, which is the irreversible part of viscoelastic deformation. In the case of elastic deformations, the response function linking strain to the deforming stress is the compliance tensor of the material.
  • 3.2K
  • 11 Nov 2022
Topic Review
Specific Relative Angular Momentum
In celestial mechanics the specific relative angular momentum [math]\displaystyle{ \vec{h} }[/math] plays a pivotal role in the analysis of the two-body problem. One can show that it is a constant vector for a given orbit under ideal conditions. This essentially proves Kepler's second law. It's called specific angular momentum because it's not the actual angular momentum [math]\displaystyle{ \vec{L} }[/math], but the angular momentum per mass. Thus, the word "specific" in this term is short for "mass-specific" or divided-by-mass: Thus the SI unit is: m2·s−1. [math]\displaystyle{ m }[/math] denotes the reduced mass [math]\displaystyle{ \frac{1}{m} = \frac{1}{m_1}+\frac{1}{m_2} }[/math].
  • 3.1K
  • 11 Nov 2022
Topic Review
Types of Snow
Types of snow can be designated by the shape of its flakes, description of how it is falling, and by how it collects on the ground. A blizzard and snow storm indicate heavy snowfalls over a large area, snow squalls give heavy snowfalls over narrow bands, while flurries are used for the lightest snowfall. Types which fall in the form of a ball, rather than a flake, are known as graupel, with sleet and snow grains as types of graupel. Once on the ground, snow can be categorized as powdery when fluffy, granular when it begins the cycle of melting and refreezing, and crud or eventually ice once it packs down into a dense drift after multiple melting and refreezing cycles. When powdering, snow drifts with the wind or ground blizzard, sometimes to the depth of several metres. After attaching to hillsides, blown snow can evolve into a snow slab, which is an avalanche hazard on steep slopes.
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  • 04 Nov 2022
Topic Review
Wake
In fluid dynamics, a wake may either be: 1. the region of recirculating flow immediately behind a moving or stationary blunt body, caused by viscosity, which may be accompanied by flow separation and turbulence, or 2. the wave pattern on the water surface downstream of an object in a flow, or produced by a moving object (e.g. a ship), caused by density differences of the fluids above and below the free surface and gravity (or surface tension).
  • 3.1K
  • 08 Nov 2022
Biography
Arthur Conan Doyle
Sir Arthur Ignatius Conan Doyle KStJ DL (22 May 1859 – 7 July 1930) was a British writer and physician. He created the character Sherlock Holmes in 1887 for A Study in Scarlet, the first of four novels and fifty-six short stories about Holmes and Dr. Watson. The Sherlock Holmes stories are considered milestones in the field of crime fiction. Doyle was a prolific writer; other than Holmes sto
  • 3.0K
  • 06 Dec 2022
Topic Review
Kairos
Kairos (καιρός) is an Ancient Greek word meaning the right, critical, or opportune moment. The ancient Greeks had two words for time: chronos (χρόνος) and kairos. The former refers to chronological or sequential time, while the latter signifies a proper or opportune time for action. While chronos is quantitative, kairos has a qualitative, permanent nature. Kairos also means weather in Modern Greek. The plural, καιροί (kairoi (Ancient and Modern Greek)) means the times. Kairos is a term, idea, and practice that has been applied in several fields including classical rhetoric, modern rhetoric, digital media, Christian theology, and science.
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  • 07 Oct 2022
Topic Review
History of Nanotechnology
The history of nanotechnology traces the development of the concepts and experimental work falling under the broad category of nanotechnology. Although nanotechnology is a relatively recent development in scientific research, the development of its central concepts happened over a longer period of time. The emergence of nanotechnology in the 1980s was caused by the convergence of experimental advances such as the invention of the scanning tunneling microscope in 1981 and the discovery of fullerenes in 1985, with the elucidation and popularization of a conceptual framework for the goals of nanotechnology beginning with the 1986 publication of the book Engines of Creation. The field was subject to growing public awareness and controversy in the early 2000s, with prominent debates about both its potential implications as well as the feasibility of the applications envisioned by advocates of molecular nanotechnology, and with governments moving to promote and fund research into nanotechnology. The early 2000s also saw the beginnings of commercial applications of nanotechnology, although these were limited to bulk applications of nanomaterials rather than the transformative applications envisioned by the field.
  • 2.8K
  • 17 Oct 2022
Topic Review
Mode-locking
Mode-locking is a technique in optics by which a laser can be made to produce pulses of light of extremely short duration, on the order of picoseconds (10−12 s) or femtoseconds (10−15 s). A laser operated in this way is sometimes referred to as a femtosecond laser, for example in modern refractive surgery. The basis of the technique is to induce a fixed-phase relationship between the longitudinal modes of the laser's resonant cavity. Constructive interference between these modes can cause the laser light to be produced as a train of pulses. The laser is then said to be 'phase-locked' or 'mode-locked'.
  • 2.8K
  • 03 Nov 2022
Topic Review
Steady State Model
In cosmology, the steady state model is an alternative to the Big Bang theory of the evolution of our universe. In the steady state model, the density of matter in the expanding universe remains unchanged due to a continuous creation of matter, thus adhering to the perfect cosmological principle, a principle that asserts that the observable universe is basically the same at any time as well as at any place. While the steady state model enjoyed some popularity in the mid-20th century (though less popularity than the Big Bang theory), it is now rejected by the vast majority of cosmologists, astrophysicists and astronomers, as the observational evidence points to a hot Big Bang cosmology with a finite age of the universe, which the steady state model does not predict.
  • 2.7K
  • 14 Oct 2022
Topic Review
Power
In physics, power is the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one joule per second. In older works, power is sometimes called activity. Power is a scalar quantity. Power is related to other quantities; for example, the power involved in moving a ground vehicle is the product of the traction force on the wheels and the velocity of the vehicle. The output power of a motor is the product of the torque that the motor generates and the angular velocity of its output shaft. Likewise, the power dissipated in an electrical element of a circuit is the product of the current flowing through the element and of the voltage across the element.
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  • 31 Oct 2022
Topic Review
Ionizing Irradiations in Food Industry
The ionizing radiations are particles or waves containing enough energy to ionize the matter when coming in contact. Their mode of action in living cells involves either the direct destruction of nucleic acid or by creating free radicals that can attack the cellular components. This cellular destruction and inactivation can be used to reduce the microbial burden in food items to increase the shelf life and safety of food, meanwhile maintaining the quality of the product. Although this technology is accepted by more than 60 countries, some consumers are reluctant to buy such products thinking that radiations might have modified their food which can also induce changes in their body after consumption. The proper scientific communication regarding the safety of ionization irradiations can change consumer behavior, and it requires the collaboration of all stakeholders in the food production chain. 
  • 2.3K
  • 05 Nov 2020
Biography
Derek J. de Solla Price
Derek John de Solla Price (22 January 1922 – 3 September 1983) was a physicist, historian of science, and information scientist, credited as the father of scientometrics.[1][2] Price was born in Leyton, England , to Philip Price, a tailor, and Fanny de Solla, a singer. He began work in 1938 as an assistant in a physics laboratory at the South West Essex Technical College, before studying P
  • 2.3K
  • 14 Nov 2022
Topic Review
Homogeneity
In physics, a homogeneous material or system has the same properties at every point; it is uniform without irregularities. A uniform electric field (which has the same strength and the same direction at each point) would be compatible with homogeneity (all points experience the same physics). A material constructed with different constituents can be described as effectively homogeneous in the electromagnetic materials domain, when interacting with a directed radiation field (light, microwave frequencies, etc.). Mathematically, homogeneity has the connotation of invariance, as all components of the equation have the same degree of value whether or not each of these components are scaled to different values, for example, by multiplication or addition. Cumulative distribution fits this description. "The state of having identical cumulative distribution function or values".
  • 2.3K
  • 15 Nov 2022
Biography
Ashoke Sen
Ashoke Sen, FRS (/əˈʃoʊk sɛn/; born 1956) is an Indian theoretical physicist and distinguished professor at the Harish-Chandra Research Institute, Allahabad.[1] He is also an honorary fellow in National Institute of Science Education and Research (NISER), Bhubaneswar, India [2] and also a Morningstar Visiting professor at MIT and a distinguished professor at the Korea Institute for Advanced
  • 2.2K
  • 16 Nov 2022
Topic Review
Asymmetric Conductivity in Heavy-Fermion Metals
We consider the time reversal T and particle-antiparticle C symmetries that, being most fundamental, can be violated at microscopic level by a weak interaction. The notable example here is from condensed matter, where strongly correlated Fermi systems like HF metals and high-Tc superconductors (or HF compounds) exhibit C and T symmetries violation due to the so-called non-Fermi liquid (NFL) behavior rather than to microscopic inter-particle interaction. When a HF compound is near the topological fermion condensation quantum phase transition (FCQPT), it exhibits the NFL properties, so that the C symmetry breaks down, making the differential tunneling conductivity to be an asymmetric function of the bias voltage V. This asymmetry does not take place in normal metals, where Landau Fermi liquid (LFL) theory holds. Under the application of magnetic field, a HF compound transits to the LFL state, and σ(V) becomes symmetric function of V. These findings are in good agreement with experimental observations. We suggest that the same topological FCQPT defines the baryon asymmetry in the Universe. Thus, the most fundamental features of the nature are defined by its topological and symmetry properties.
  • 2.2K
  • 29 Apr 2021
Topic Review
Moment
In physics, a moment is a mathematical expression involving the product of a distance and physical quantity. Moments are usually defined with respect to a fixed reference point and refer to physical quantities located some distance from the reference point. In this way, the moment accounts for the quantity's location or arrangement. For example, the moment of force, often called torque, is the product of a force on an object and the distance from the reference point to the object. In principle, any physical quantity can be multiplied by a distance to produce a moment. Commonly used quantities include forces, masses, and electric charge distributions.
  • 2.2K
  • 07 Nov 2022
Topic Review
Tensile Testing
Tensile testing, also known as tension testing, is a fundamental materials science and engineering test in which a sample is subjected to a controlled tension until failure. Properties that are directly measured via a tensile test are ultimate tensile strength, breaking strength, maximum elongation and reduction in area. From these measurements the following properties can also be determined: Young's modulus, Poisson's ratio, yield strength, and strain-hardening characteristics. Uniaxial tensile testing is the most commonly used for obtaining the mechanical characteristics of isotropic materials. Some materials use biaxial tensile testing. The main difference between these testing machines being how load is applied on the materials.
  • 2.1K
  • 23 Nov 2022
Topic Review
Raksha Bandhan
Raksha Bandhan, also Rakshabandhan, or Rakhi, is a popular, traditionally Hindu, annual rite, or ceremony, which is central to a festival of the same name, celebrated in parts of South Asia, and among people influenced by South Asian culture around the world. On this day, sisters of all ages tie a talisman, or amulet, called the rakhi, around the wrists of their brothers, symbolically protecting them, receiving a gift in return, and traditionally investing the brothers with a share of the responsibility of their potential care. Raksha Bandhan is observed on the last day of the Hindu lunar calendar month of Shraavana, which typically falls in August. The expression "Raksha Bandhan," Sanskrit, literally, "the bond of protection, obligation, or care," is now principally applied to this ritual. Until the mid-20th-century, the expression was more commonly applied to a similar ritual, also held on the same day, with precedence in ancient Hindu texts, in which a domestic priest ties amulets, charms, or threads on the wrists of his patrons, or changes their sacred thread, and receives gifts of money; in some places, this is still the case. In contrast, the sister-brother festival, with origins in folk culture, had names which varied with location, with some rendered as Saluno, Silono, and Rakri. A ritual associated with Saluno included the sisters placing shoots of barley behind the ears of their brothers. Of special significance to married women, Raksha Bandhan is rooted in the practice of territorial or village exogamy, in which a bride marries out of her natal village or town, and her parents, by custom, do not visit her in her married home. In rural north India, where village exogamy is strongly prevalent, large numbers of married Hindu women travel back to their parents' homes every year for the ceremony. Their brothers, who typically live with the parents or nearby, sometimes travel to their sisters' married home to escort them back. Many younger married women arrive a few weeks earlier at their natal homes and stay until the ceremony. The brothers serve as lifelong intermediaries between their sisters' married and parental homes, as well as potential stewards of their security. In urban India, where families are increasingly nuclear, the festival has become more symbolic, but continues to be highly popular. The rituals associated with this festival have spread beyond their traditional regions and have been transformed through technology and migration, the movies, social interaction, and promotion by politicized Hinduism, as well as by the nation state. Among women and men who are not blood relatives, there is also a transformed tradition of voluntary kin relations, achieved through the tying of rakhi amulets, which have cut across caste and class lines, and Hindu and Muslim divisions. In some communities or contexts, other figures, such as a matriarch, or a person in authority, can be included in the ceremony in ritual acknowledgement of their benefaction.
  • 2.1K
  • 18 Oct 2022
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