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Topic Review
Two-Dimensional Materials
Two-dimensional (2D) materials are defined as crystalline materials consisting of single- or few-layer atoms, in which the in-plane interatomic interactions are much stronger than those along the stacking direction. Since the success of monolayer graphene exfoliation, 2D materials have been extensively studied due to their unique structures and unprecedented properties. Among these fascinating studies, the most predominant focus has been on their atomic structures, defects, and mechanical behaviors and properties, which serve as the basis for the practical applications of 2D materials.
  • 18.2K
  • 07 Jan 2022
Topic Review
Closed Timelike Curves
Closed timelike curves (CTCs) are space-time trajectories that return to their starting point without violating the laws of special relativity. A traveler along a CTC could journey into the future but arrive in its past, creating a possible violation of the principle of causality. Such CTCs occur in Gödel’s rotating universe and many other general relativistic solutions of classical Einstein’s field equations. The chronological protection conjecture suggests that Nature forbids this kind of situation.
  • 18.1K
  • 27 Jan 2021
Topic Review
Zodiac
The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets are within the belt of the zodiac. In Western astrology, and formerly astronomy, the zodiac is divided into twelve signs, each occupying 30° of celestial longitude and roughly corresponding to the following star constellations: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. These astrological signs form a celestial coordinate system, or more specifically an ecliptic coordinate system, which takes the ecliptic as the origin of latitude and the Sun's position at vernal equinox as the origin of longitude.
  • 18.1K
  • 31 Oct 2022
Topic Review
Standard Conditions for Temperature and Pressure
Standard temperature and pressure (STP) are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST), although these are not universally accepted standards. Other organizations have established a variety of alternative definitions for their standard reference conditions. In chemistry, IUPAC changed the definition of standard temperature and pressure in 1982: STP should not be confused with the standard state commonly used in thermodynamic evaluations of the Gibbs energy of a reaction. NIST uses a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 1 atm (14.696 psi, 101.325 kPa). This standard is also called normal temperature and pressure (abbreviated as NTP). These stated values of STP used by NIST have not been verified and require a source. However, values cited in Modern Thermodynamics with Statistical Mechanics by Carl S. Helrich and A Guide to the NIST Chemistry WebBook by Peter J. Linstrom suggest a common STP in use by NIST for thermodynamic experiments is 298.15 K (25°C, 77°F) and 1 bar (14.5038 psi, 100 kPa). The International Standard Metric Conditions for natural gas and similar fluids are 288.15 K (15.00 °C; 59.00 °F) and 101.325 kPa. In industry and commerce, standard conditions for temperature and pressure are often necessary to define the standard reference conditions to express the volumes of gases and liquids and related quantities such as the rate of volumetric flow (the volumes of gases vary significantly with temperature and pressure): standard cubic meters per second (Sm3/s), and normal cubic meters per second (Nm3/s). However, many technical publications (books, journals, advertisements for equipment and machinery) simply state "standard conditions" without specifying them; often substituting the term with older "normal conditions", or "NC". In special cases this can lead to confusion and errors. Good practice always incorporates the reference conditions of temperature and pressure. If not stated, some room environment conditions are supposed, close to 1 atm pressure, 293 K (20 °C), and 0% humidity.
  • 18.1K
  • 09 Nov 2022
Topic Review
Women in Shinto
Women in Shinto occupy a unique role in the indigenous Japanese traditions of Shinto, including a unique form of participation as temple stewards and shamans, or miko. Though a ban on Shinto priestesses was lifted after 1945, the number of women priests in Shinto is a small fraction of contemporary clergy.
  • 18.1K
  • 17 Oct 2022
Topic Review
Direct Rule
Direct rule is when an imperial or central power takes direct control over the legislature, executive and civil administration of an otherwise largely self-governing territory.
  • 18.0K
  • 01 Nov 2022
Topic Review
Social System
A social system refers to a complex network of interrelated social entities, such as individuals, groups, organizations, and institutions, that interact and influence one another within a shared environment or society. These interactions are guided by norms, values, roles, and patterns of behavior, which collectively shape the functioning and structure of the social system. Social systems exhibit patterns of organization, stability, and adaptation, serving various functions and purposes within society.
  • 17.9K
  • 02 Feb 2024
Topic Review
Flavonoids—Classification and Natural Sources
       Flavonoids are small molecules, produced de novo by plants as secondary metabolites in response to diverse biotic and abiotic factors. These chemical compounds have a broad spectrum of established health-promoting effects. They are due to their antioxidative, anti-inflammatory, anti-mutagenic, and anti-carcinogenic properties coupled with their capacity to modulate key cellular enzyme functions. Flavonoids are widely distributed chemical compounds in the plant kingdom. Plants are therefore an inexhaustible source of flavonoids.
  • 17.8K
  • 02 Nov 2020
Topic Review
Custodial Death of P Jayaraj and Bennicks
On 19 June 2020, P. Jayaraj (59 years old) and his son J. Bennicks (also spelled Fennix, Bennix) (31 years old) were picked up for inquiry by the Tamil Nadu Police in Sathankulam, Thoothukudi district for allegedly violating the Indian government's COVID-19 lockdown rules. According to the police, the duo was held for allegedly keeping their mobile accessories shop open beyond permissible hours on June 19. An FIR was filed against the two on 19 June and both were taken into custody. However CBI in chargesheet claimed there were no violation of the lockdown rules. they were sexually assaulted and tortured by the police while in custody, leading to their deaths. On 22 June 2020, Bennicks fell ill and was moved to the Kovilpatti General Hospital, where he died later that day. The following day, 22 June 2020, his father also died. The custodial death of the two men in Tamil Nadu's Sathankulam town in Thoothukudi district sparked massive outrage in the state over police brutality.
  • 17.7K
  • 19 Oct 2022
Topic Review
Suetonius on Christians
The Roman historian Suetonius (c. AD 69 – c. AD 122) mentions early Christians and may refer to Jesus Christ in his work Lives of the Twelve Caesars. One passage in the biography of the Emperor Claudius Divus Claudius 25, refers to agitations in the Roman Jewish community and the expulsion of Jews from Rome by Claudius during his reign (AD 41 to AD 54), which may be the expulsion mentioned in the Acts of the Apostles (18:2). In this context "Chresto" is mentioned. Some scholars see this as a likely reference to Jesus, while others see it as referring to an otherwise unknown person living in Rome. Christians are explicitly mentioned in Suetonius' biography of the Emperor Nero (Nero 16) as among those punished during Nero's reign. These punishments are generally dated to around AD 64, the year of the Great Fire of Rome. In this passage Suetonius describes Christianity as excessive religiosity (superstitio) as do his contemporaries, Tacitus and Pliny. Historians debate whether or not the Roman government distinguished between Christians and Jews prior to Nerva's modification of the Fiscus Judaicus in AD 96. From then on, practising Jews paid the tax, Christians did not.
  • 17.6K
  • 17 Nov 2022
Topic Review
Chinese Swords
Historically, all Chinese swords are classified into two types, jian and dao. Jians are double-edged straight swords while daos are single-edged, and mostly curved from the Song dynasty forward. The jian has been translated at times as a long sword, and the dao a saber or a knife. Bronze jians appeared during the Western Zhou period and switched to wrought iron and steel during the late Warring States period. In modern times, the ceremonial commissioned officer's sword of the Chinese navy has been patterned after the traditional jian since 2008. Other than specialized weapons like the Divided Dao, Chinese swords are usually 70–110 cm (28–43 in) in length, although longer swords have been found on occasion. Outside of China, Chinese swords were also used in Japan from the third to the sixth century AD, but were replaced with Korean and native Japanese swords by the middle Heian era.
  • 17.6K
  • 30 Sep 2022
Topic Review
Ievan Polkka
"Ievan Polkka" or "Ievan Polokka" (Savo Finnish for "Eva's Polka") is a popular Finland song with lyrics written in the early 1930s by Eino Kettunen to a traditional Finnish polka tune. The name is commonly misspelled Levan Polkka, due to the similarity of lowercase L and the uppercase vowel I (i) in sans-serif fonts. It is also known as "Loituma's Polka" (or "Loituma's Polkka").
  • 17.6K
  • 15 Nov 2022
Topic Review
Countries Blocking Access to The Pirate Bay
This is a list of countries where at least one internet service provider (ISP) formerly or currently censors the popular file sharing website The Pirate Bay (TPB).
  • 17.5K
  • 29 Nov 2022
Topic Review
Global South
The Global South is a term often used to identify lower-income countries on one side of the so-called global North–South divide, the other side being the countries of the Global North. As such the term does not inherently refer to a geographical south; for example, most of the Global South is actually within the Northern Hemisphere. The term, as used by governmental and development organizations, was first introduced as a more open and value free alternative to "Third World" and similar potentially "valuing" terms like developing countries. Countries of the Global South have been described as newly industrialized or in the process of industrializing and frequently have a history of colonialism by Northern, often European, states. The countries of Brazil, China, India, Indonesia, and Mexico have the largest populations and economies among Southern states. The overwhelming majority of these countries are located in or near the tropics.
  • 17.5K
  • 14 Oct 2022
Topic Review
Nasolabial Angle in Orthodontic Diagnosis
The nasolabial angle (NLA) is one of the key factors to be studied in an orthodontic diagnosis for the aesthetics of the nose and facial profile.
  • 17.5K
  • 06 Feb 2022
Topic Review
Ivermectin as Broad-Spectrum Host-Directed Antiviral
The small molecule macrocyclic lactone ivermectin, approved by the US Food and Drug Administration for parasitic infections, has received attention in the last eight years due to its exciting potential as an antiviral. It was identified in a high-throughput chemical screen as inhibiting recognition of the nuclear localizing Human Immunodeficiency Virus 1 (HIV-1) integrase protein by the host heterodimeric importin (IMP) α/β1 complex, and has since been shown to bind directly to IMPα to induce conformational changes that prevent its normal function in mediating nuclear import of key viral and host proteins. Excitingly, cell culture experiments show robust antiviral action towards HIV-1, dengue virus (DENV), Zika virus, West Nile virus, Venezuelan equine encephalitis virus, Chikungunya virus, Pseudorabies virus, adenovirus, and SARS-CoV-2 (COVID-19). Phase III human clinical trials have been completed for DENV, with >60 trials currently in progress worldwide for SARS-CoV-2.
  • 17.4K
  • 30 Sep 2020
Topic Review
Higher Education and COVID-19
The COVID-19 pandemic had profound consequences on the educational dimension, with the temporary closure of educational institutions, as well as the impediment of face-to-face classes. These challenging conditions can be a critical moment of opportunity to reshape education in higher education, with the implementation, development, and diffusion of digital technologies.
  • 17.3K
  • 20 Oct 2020
Topic Review
Plant Embryogenesis
Plant embryogenesis is a process that occurs after the fertilization of an ovule to produce a fully developed plant embryo. This is a pertinent stage in the plant life cycle that is followed by dormancy and germination. The zygote produced after fertilization must undergo various cellular divisions and differentiations to become a mature embryo. An end stage embryo has five major components including the shoot apical meristem, hypocotyl, root meristem, root cap, and cotyledons. Unlike animal embryogenesis, plant embryogenesis results in an immature form of the plant, lacking most structures like leaves, stems, and reproductive structures. However, both plants and animals pass through a phylotypic stage that evolved independently and that causes a developmental constraint limiting morphological diversification.
  • 17.2K
  • 28 Apr 2023
Topic Review
Elephantinae
Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are an informal grouping within the proboscidean family Elephantidae. Elephantidae is the only surviving family of proboscideans; extinct members include the mastodons. Elephantidae also contains several extinct groups, including the mammoths and straight-tusked elephants. African elephants have larger ears and concave backs, whereas Asian elephants have smaller ears, and convex or level backs. The distinctive features of all elephants include a long proboscis called a trunk, tusks, large ear flaps, massive legs, and tough but sensitive skin. The trunk is used for breathing, bringing food and water to the mouth, and grasping objects. Tusks, which are derived from the incisor teeth, serve both as weapons and as tools for moving objects and digging. The large ear flaps assist in maintaining a constant body temperature as well as in communication. The pillar-like legs carry their great weight. Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia and are found in different habitats, including savannahs, forests, deserts, and marshes. They are herbivorous, and they stay near water when it is accessible. They are considered to be keystone species, due to their impact on their environments. Elephants have a fission–fusion society, in which multiple family groups come together to socialise. Females (cows) tend to live in family groups, which can consist of one female with her calves or several related females with offspring. The groups, which do not include bulls, are usually led by the oldest cow, known as the matriarch. Males (bulls) leave their family groups when they reach puberty and may live alone or with other males. Adult bulls mostly interact with family groups when looking for a mate. They enter a state of increased testosterone and aggression known as musth, which helps them gain dominance over other males as well as reproductive success. Calves are the centre of attention in their family groups and rely on their mothers for as long as three years. Elephants can live up to 70 years in the wild. They communicate by touch, sight, smell, and sound; elephants use infrasound, and seismic communication over long distances. Elephant intelligence has been compared with that of primates and cetaceans. They appear to have self-awareness, and appear to show empathy for dying and dead family members. African bush elephants and Asian elephants are listed as endangered and African forest elephants as critically endangered by the International Union for Conservation of Nature (IUCN). One of the biggest threats to elephant populations is the ivory trade, as the animals are poached for their ivory tusks. Other threats to wild elephants include habitat destruction and conflicts with local people. Elephants are used as working animals in Asia. In the past, they were used in war; today, they are often controversially put on display in zoos, or exploited for entertainment in circuses. Elephants are highly recognisable and have been featured in art, folklore, religion, literature, and popular culture.
  • 17.2K
  • 10 Oct 2022
Topic Review
In-Vehicle Networks
Modern vehicles are no longer simply mechanical devices. Connectivity between the vehicular network and the outside world has widened the security holes that hackers can use to exploit a vehicular network. Controller Area Network (CAN), FlexRay, and automotive Ethernet are popular protocols for in-vehicle networks (IVNs) and will stay in the industry for many more years. However, these protocols were not designed with security in mind. They have several vulnerabilities, such as lack of message authentication, lack of message encryption, and an ID-based arbitration mechanism for contention resolution. Adversaries can use these vulnerabilities to launch sophisticated attacks that may lead to loss of life and damage to property. Thus, the security of the vehicles should be handled carefully. In this paper, we investigate the security vulnerabilities with in-vehicle network protocols such as CAN, automotive Ethernet, and FlexRay. A comprehensive survey on security attacks launched against in-vehicle networks is presented along with countermeasures adopted by various researchers. Various algorithms have been proposed in the past for intrusion detection in IVNs. However, those approaches have several limitations that need special attention from the research community. Blockchain is a good approach to solving the existing security issues in IVNs, and we suggest a way to improve IVN security based on a hybrid blockchain.
  • 17.2K
  • 15 Apr 2021
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