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Topic Review
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Topic Review
Free-Space Optical Communication
Fast communication is of high importance. Recently, increased data demand and crowded radio frequency spectrum have become crucial issues. Free-Space Optical Communication (FSOC) has diametrically changed the way people exchange information. As an alternative to wire communication systems, it allows efficient voice, video, and data transmission using a medium like air. Due to its large bandwidth, FSOC can be used in various applications and has therefore become an important part of our everyday life. The main advantages of FSOC are a high speed, cost savings, compact structures, low power, energy efficiency, a maximal transfer capacity, and applicability. The rapid development of the high-speed connection technology allows one to reduce the repair downtime and gives the ability to quickly establish a backup network in an emergency. Unfortunately, FSOC is susceptible to disruption due to atmospheric conditions or direct sunlight. Here, we briefly discuss Free-Space Optical Communication from mirrors and optical telegraphs to modern wireless systems and outline the future development directions of optical communication.
8.3K
11 Nov 2020
Topic Review
Phanerozoic
The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 541 million years to the present and began with the Cambrian Period when animals first developed hard shells preserved in the fossil record. The time before the Phanerozoic, called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons. The time span of the Phanerozoic starts with the sudden appearance of fossilized evidence of a number of animal phyla; the evolution of those phyla into diverse forms; the emergence and development of complex plants; the evolution of fish; the emergence of insects and tetrapods; and the development of modern fauna. Plant life on land appeared in the early Phanerozoic eon. During this time span, tectonic forces caused the continents to move and eventually collect into a single landmass known as Pangaea (the most recent supercontinent), which then separated into the current continental landmasses.
8.3K
08 Oct 2022
Topic Review
Clouding of Consciousness
Clouding of consciousness (also known as brain fog or mental fog) is when a person is slightly less wakeful or aware than normal. They are not as aware of time or their surroundings and find it difficult to pay attention. People describe this subjective sensation as their mind being "foggy".
8.3K
21 Nov 2022
Topic Review
Lalitaditya Muktapida of Kashmir
Lalitaditya Muktapida of Kashmir, an eminent 8th-century ruler, is a significant yet often overlooked figure in Indian history. Known for his unparalleled military prowess, Lalitaditya never lost a battle, whether against the Arabs or his contemporaries. Beyond his martial achievements, he was a prolific builder, responsible for the construction of numerous cities and monumental structures, including the grand Martand Sun Temple and his capital, Parihaspura. His reign in Kashmir was characterised by wide territorial control and cultural flowering.
8.3K
02 Jul 2024
Topic Review
Gaming Computer
A gaming computer, also known as a gaming PC, is a specialized personal computer designed for playing video games. Gaming PCs typically differ from mainstream personal computers by using high-performance video cards and high core-count central processing units with raw performance. Gaming PCs are also used for other demanding tasks such as video editing. Many gamers and computer enthusiasts choose to overclock their CPU(s) and GPU(s) in order to gain extra performance. The added power draw needed to overclock either processing unit often requires additional cooling, using upgraded air cooling or water cooling.
8.3K
01 Nov 2022
Topic Review
Negawatt Power
Negawatt power is a theoretical unit of power representing an amount of electrical power (measured in watts) saved. The energy saved is a direct result of energy conservation or increased energy efficiency. The term was coined by the chief scientist of the Rocky Mountain Institute and environmentalist Amory Lovins in 1985, within the article, "Saving Gigabucks with Negawatts," where he argued that utility customers don’t want kilowatt-hours of electricity; they want energy services such as hot showers, cold beer, lit rooms, and spinning shafts, which can come more cheaply if electricity is used more efficiently. Lovins felt an international behavioral change was necessary in order to decrease countries' dependence on excessive amounts of energy. The concept of a negawatt could influence a behavioral change in consumers by encouraging them to think about the energy that they spend. A negawatt market can be thought of as a secondary market, in which electricity is allocated from one consumer to another consumer within the energy market. In this market, negawatts could be treated as a commodity. Commodities have the ability to be traded across time and space, which would allow negawatts to be incorporated in the international trading system. Roughly 10% of all U.S. electrical generating capacity is in place to meet the last 1% of demand and there is where the immediate efficiency opportunity exists. On March 15, 2011, the Federal Energy Regulatory Commission (FERC), the agency that regulates the U.S. electrical grid, approved a rule establishing the approach to compensation for demand response resources intended to benefit customers and help improve the operation and competitiveness of organized wholesale energy markets. This means that negawatts produced by reducing electrical use can demand the same market prices as real megawatts of generated electricity. The incentives for a negawatt market include receiving money, reduction of national energy dependency, and the local electricity deregulation within certain nations or states. As for the cost incentive, those who produce negawatts or simply conserve energy can earn money by selling the saved energy. The negawatt market could help nations or states obtain a deregulated electricity system by creating another market to purchase electricity from. The negawatt market also has two main drawbacks. Currently, there is no way to precisely measure the amount of energy saved in negawatts, and electricity providers may not want customers to use less energy due to the loss of profit.
8.3K
22 Nov 2022
Topic Review
History and Development of Nanomaterial Research
Scientists think that nanoparticles and nanostructured materials originated during the Big Bang process from meteorites leading to the formation of the universe and Earth. Since 1990, the term nanotechnology became very popular due to advances in imaging technologies that paved the way to specific industrial applications.
8.3K
09 Feb 2022
Topic Review
Aether (Classical Element)
According to ancient and medieval science, aether (/ˈiːθər/), also spelled æther, aither, or ether and also called quintessence, is the material that fills the region of the universe above the terrestrial sphere. The concept of aether was used in several theories to explain several natural phenomena, such as the traveling of light and gravity. In the late 19th century, physicists postulated that aether permeated all throughout space, providing a medium through which light could travel in a vacuum, but evidence for the presence of such a medium was not found in the Michelson–Morley experiment, and this result has been interpreted as meaning that no such luminiferous aether exists.
8.3K
02 Oct 2022
Topic Review
Schismogenesis
Schismogenesis literally means "creation of division". The term derives from the Greek words σχίσμα skhisma "cleft" (borrowed into English as schism, "division into opposing factions"), and γένεσις genesis "generation, creation" (deriving in turn from gignesthai "be born or produced, creation, a coming into being").
8.3K
30 Nov 2022
Topic Review
Doctor of Engineering
The Doctor of Engineering, or Engineering Doctorate, (abbreviated Eng.D., D.Eng., D.Engr., Dr.Eng., or Dr.-Ing.) is a degree awarded on the basis of advanced study and research in engineering and applied sciences. In most countries, it is a terminal research doctorate. A DEng/EngD is equivalent to a PhD in engineering, but different in that it has a solid industrial base and an additional taught element. The DEng/EngD along with the PhD represents the highest academic qualification in engineering, and the successful completion of either in engineering is generally required to gain employment as a full-time, tenure-track university professor or postdoctoral researcher in the field. Individuals can use the academic title doctor, which is often represented via the English honorific "Dr”. DEng/EngD candidates submit a significant project, typically referred to as a thesis or praxis, consisting of a body of original applied research that may be in principle worthy of publication in a peer-reviewed journal. Candidates must defend this work before a panel of expert examiners called a thesis or dissertation committee.
8.3K
20 Oct 2022
Topic Review
Sensor Technology in Autonomous Vehicles
With the significant advancement of sensor and communication technology and the reliable application of obstacle detection techniques and algorithms, automated driving is becoming a pivotal technology that can revolutionize the future of transportation and mobility. Sensors are fundamental to the perception of vehicle surroundings in an automated driving system, and the use and performance of multiple integrated sensors can directly determine the safety and feasibility of automated driving vehicles.
8.3K
31 Mar 2021
Topic Review
Kingdom
In biology, a kingdom (Latin: regnum, plural regna) is the second highest taxonomic rank, just below domain. Kingdoms are divided into smaller groups called phyla. Traditionally, some textbooks from the United States and Canada used a system of six kingdoms (Animalia, Plantae, Fungi, Protista, Archaea/Archaebacteria, and Bacteria/Eubacteria) while textbooks in Great Britain, India, Greece, Brazil and other countries use five kingdoms only (Animalia, Plantae, Fungi, Protista and Monera). Some recent classifications based on modern cladistics have explicitly abandoned the term kingdom, noting that some traditional kingdoms are not monophyletic, meaning that they do not consist of all the descendants of a common ancestor. The terms flora (for plants), fauna (for animals), and, in the 21st century, funga (for fungi) are also used for life present in a particular region or time.
8.3K
27 Nov 2022
Topic Review
Battery Management System Subsystems and Their Influence
As the battery provides the entire propulsion power in electric vehicles (EVs), the utmost importance should be ascribed to the battery management system (BMS) which controls all the activities associated with the battery.
8.2K
28 Jun 2022
Topic Review
List of Assyrian Tribes
This page features a list of Assyrian clans or tribes historically centered in the Hakkari, Sirnak and Mardin provinces in Turkey and West Azerbaijan Province in Iran, prior to 1915, or before Seyfo, when they were historically Assyrian settlements, before early 20th century resettlement in Northern Iraq (which simultaneously had Catholic-Assyrian tribes since the 1st millennium) and northwestern Syria (namely in Al-Hasakah) after they were displaced, slaughtered and driven out by Ottoman Turks in 1915 and in the early 1930s, respectively, during the Simele massacre where they endured a similar anguish and predicament. From around 2500 BC, Assyrians primarily lived in the ancient Assyrian cities of Nineveh, Assur, Nohadra, Arrapha and Arbela, which now lie in modern-day northern Iraq, and as well as the mountainous Assyrian region of Hakkari in what is now Turkey, from around 2300 BC. Though after the spread of Islam, many eventually left the ancient Assyrian cities in the Nineveh Plains, where they settled and found refuge in the highland region in southeastern Anatolia, with the existing Assyrian population, and northwestern Iran. The villages in southeastern Turkey are primarily centred in the modern-day towns of Yuksekova, Çukurca and Semdinli in Hakkâri, Uludere in Sirnak Province and Tur Abdin in Mardin Province. Most of the historical Assyrian tribes are located in the region stretching from Tur Abdin to Hakkari, in Upper Mesopotamia, which formed the Nairi lands, serving as the northern Assyrian frontier and border with their Urartian rivals. The Assyrians of this region were Nestorian Christians adhering to the Assyrian Church of the East and lived here until 1924, when the very last Assyrians who survived the Assyrian Genocide and massacres that occurred during 1918 were expelled. Most subsequently moved to the Nahla valley in northern Iraq or elsewhere. The people of these tribes are an ancient people of Mesopotamia who speak Assyrian Neo-Aramaic, a modern Syriac language that's derived from old Aramaic and has influences of Akkadian. In the early-mid 20th century, most settled in Iraq, Jordan, Syria and Iran, where many eventually immigrated to the western world in recent years.
8.2K
02 Dec 2022
Topic Review
Black Ginseng
Black ginseng is a processed ginseng which prepared by steaming and drying of white or red ginseng for several times (usually 9). This process resulting in extensive changes in types and amounts of several secondary metabolites. Thus, primary ginsenosides (the main active inredients in ginseng) were transformed into less polar derivatives by steaming. In addition, apparent changes happened to other secondary metabolites such as the increasing of phenolic compounds, reducing sugars and acidic polysaccharides as well as the decrease in concentrations of free amino acids and total polysaccharides. Furthermore, the presence of some Maillard reaction products like maltol was also engaged. These obvious chemical changes were associated with a noticeable superiority for black ginseng over white and red ginseng in most of the comparative biological studies including anticarcinogenic, immunomodulatory, anti-Inflammatory, antidiabetic, hepatoprotective, antioxidant and tonic effects.
8.2K
30 Oct 2020
Topic Review
Probability Sampling and Non Probability Sampling
There are two types of sampling methods namely: probability sampling and non-probability sampling. Each of these methods includes different types of techniques of sampling. Non-probability Sampling includes Quota sampling, Snowball sampling, Judgment sampling, and Convenience sampling, furthermore, Probability Sampling includes Simple random, Stratified random, Cluster sampling, Systematic sampling and Multi stage sampling.
8.2K
18 Feb 2022
Topic Review
Internet Archive
Coordinates: 37°46′56″N 122°28′18″W / 37.782321°N 122.47161137°W / 37.782321; -122.47161137 The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge".[notes 2][notes 3] It provides free public access to collections of digitized materials, including websites, software applications/games, music, movies/videos, moving images, and millions of books. In addition to its archiving function, the Archive is an activist organization, advocating a free and open Internet. As of April 2021, the Internet Archive holds over 30 million books and texts, 8.9 million movies, videos and TV shows, 649,000 software programs, 13,225,000 audio files, 3.8 million images, and 580 billion web pages in the Wayback Machine. The Internet Archive allows the public to upload and download digital material to its data cluster, but the bulk of its data is collected automatically by its web crawlers, which work to preserve as much of the public web as possible. Its web archive, the Wayback Machine, contains hundreds of billions of web captures.[notes 4] The Archive also oversees one of the world's largest book digitization projects.
8.2K
18 Oct 2022
Topic Review
Vitamin B6 and Diabetes
Vitamin B6 is an essential nutrient for the human health. It is involved in more that 150 metabolic reactions which regulate the metabolism of glucose, lipids, amino acids, DNA, and neurotransmitters. In addition, vitamin B6 is an antioxidant molecule able to counteracting the formation of reactive oxygen species (ROS) and advanced glycation end-products (AGEs). Epidemiological and experimental studies indicated the reduced levels of vitamin B6 can cause diabetes. In contrast other studies show that diabetes decreases vitamin B6 levels. Thus these findings lead to envisage the existence of a vicious circle at the basis of the relationship between vitamin B6 and diabetes. This entry reports the main evidence concerning the role of vitamin B6 in diabetes and examine the underlying molecular and cellular mechanisms.
8.2K
28 Oct 2020
Topic Review
Paschen's Law
Paschen's law is an equation that gives the breakdown voltage, that is, the voltage necessary to start a discharge or electric arc, between two electrodes in a gas as a function of pressure and gap length. It is named after Friedrich Paschen who discovered it empirically in 1889. Paschen studied the breakdown voltage of various gases between parallel metal plates as the gas pressure and gap distance were varied: For a given gas, the voltage is a function only of the product of the pressure and gap length. The curve he found of voltage versus the pressure-gap length product (right) is called Paschen's curve. He found an equation that fit these curves, which is now called Paschen's law. At higher pressures and gap lengths, the breakdown voltage is approximately proportional to the product of pressure and gap length, and the term Paschen's law is sometimes used to refer to this simpler relation. However, this is only roughly true, over a limited range of the curve.
8.2K
09 Nov 2022
Topic Review
Anaphase Bridges
Anaphase bridges are DNA threads stretching between the two DNA masses as cells attempt to segregate them during anaphase. Anaphase bridges arise from unresolved DNA intertwines between sister chromatids. Sister chromatid intertwines (SCIs) naturally arise during DNA replication and represent a non-proteinaceous source of cohesion between sister chromatids. SCIs and are mainly resolved in S phase, although some do persist and must be fully removed during mitosis to allow faithful chromosome segregation and avoid the arising of DNA lesions and genome instability, a hallmark of cancer development. As complete resolution of SCIs only occurs during chromosome segregation, it is not clear whether intertwines that persist in mitosis are simply an unwanted leftover or whether they have a functional role.
8.2K
04 Sep 2020
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