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Topic Review
Google Data Centers
Google Data Centers are the large data center facilities Google uses to provide their services, which combine large drives, computer nodes organized in aisles of racks, internal and external networking, environmental controls (mainly cooling and dehumidification), and operations software (especially as concerns load balancing and fault tolerance). There is no official data on how many servers are in Google data centers, but Gartner estimated in a July 2016 report that Google at the time had 2.5 million servers. This number is changing as the company expands capacity and refreshes its hardware.
  • 5.5K
  • 11 Nov 2022
Topic Review
Preparation of Nanofluids
There are two different ways of preparing nanofluids categorized in a one-step process and a two-step process. The origin of the word “nanofluid” is connected with the work by Choi et al. back in 1995, where they researched enhancement of thermal conductivity of fluids mixed with nanoparticles, determined the direction of further research, described the theoretical study of these fluids, and set potential benefits of nanofluids. From that point, the number of scientific papers that deal with nanofluids has been exponentially increasing. 
  • 5.5K
  • 22 Nov 2021
Topic Review
Development of Single-cell RNA Sequencing
Single-cell RNA sequencing (scRNA-seq) technology provides a powerful tool for understanding complex biosystems at the single-cell and single-molecule level. The application of droplet- and microwell-based microfluidics in scRNA-seq has contributed greatly to improving sequencing throughput. 
  • 5.5K
  • 01 Jul 2022
Topic Review
Women in Taoism
The roles of women in Taoism (/ˈdaʊɪzəm/, /ˈtaʊ-/) (also spelled "Daoism" /ˈdaʊ-/) have differed from the traditional patriarchy over women in ancient and imperial China. Chinese women had special importance in some Taoist schools that recognized their transcendental abilities to communicate with deities, who frequently granted women with revealed texts and scriptures. Women first came to prominence in the Highest Clarity School, which was founded in the 4th century by a woman, Wei Huacun. The Tang dynasty (618-907) was a highpoint for the importance of Daoist women, when one-third of the Shangqing clergy were women, including many aristocratic Daoist nuns. The number of Daoist women decreased until the 12th century when the Complete Perfection School, which ordained Sun Bu'er as the only woman among its original disciples, put women in positions of power. In the 18th and 19th centuries, women Daoists practiced and discussed nüdan (女丹, "women's neidan inner alchemy"), involving gender-specific practices of breath meditation and visualization. Furthermore, Daoist divinities and cults have long traditions in China, for example, the Queen Mother of the West, the patron of xian immortality, He Xiangu, one of the Eight Immortals, and Mazu, the protectress of sailors and fishermen.
  • 5.4K
  • 24 Nov 2022
Topic Review
Islamic State
An Islamic state is a form of government based on Islamic law. As a term, it has been used to describe various historical polities and theories of governance in the Islamic world. As translation of the Arabic term dawlah islāmiyyah (Arabic: دولة إسلامية) it refers to a modern notion associated with political Islam (Islamism). The concept of the modern Islamic state has been articulated and promoted by ideologues such as Abul A'la Maududi, Ayatollah Ruhollah Khomeini, Israr Ahmed or Sayyid Qutb. Implementation of Islamic law plays an important role in modern theories of the Islamic state, as it did in classical Islamic political theories. However, the modern theories also make use of notions that did not exist before the modern era. Today, many Muslim countries have incorporated Islamic law, wholly or in part, into their legal systems. Certain Muslim states have declared Islam to be their state religion in their constitutions, but do not apply Islamic law in their courts. Islamic states which are not Islamic monarchies are usually referred to as Islamic republics.
  • 5.4K
  • 29 Sep 2022
Topic Review
Technologies for Big Data
Big data is growing so fast that current storage technologies and analytical tools are gradually feeling their inefficiencies not only to store and manage the valuable data but also to take full advantages of the opportunities and business insights that enormous data can offer. Since 2014, the concept of a data lake is increasingly becoming a popular solution among information leaders and big data-driven companies to deal with the challenges that brought about by big data. However, due to lacking of enough established best practices or related theories, some practitioners are still being kept outside the gate to a less risky implementation of a data lake. Besides, practitioners can hardly find any references which are free of bias, such as academic researches or reports, and are hardly able to support them with the reality of building a data lake at preset from an independent perspective.  
  • 5.4K
  • 06 Jun 2021
Topic Review
Coffee Cherry Structure and Processing
Coffee bean harvesting incurs various by-products known for their long traditional use. However, they often still end up being a waste instead of being used to their full potential. On the European market, coffee cherry (cascara) products are not yet common, and a novel food approval for beverages made from coffee cherry pulp was issued only recently. 
  • 5.4K
  • 08 Dec 2022
Topic Review
Religious Naturalism
Religious naturalism (RN) combines a naturalist worldview with perceptions and values commonly associated with religions. In this, "religious" is understood in general terms, separate from established traditions, in designating feelings and concerns (e.g. gratitude, wonder, humility, compassion) that are often described as spiritual or religious. Naturalism refers to a view that the natural world is all we have substantiated reason to believe exists, and there is no substantiated reason to believe that anything else, including deities, exists or may act in ways that are independent of the natural order. Areas of inquiry include attempts to understand the natural world and the spiritual and moral implications of naturalist views. Understanding is based in knowledge obtained through scientific inquiry and insights from the humanities and the arts. Religious naturalists use these perspectives in responding to personal and social challenges (e.g. finding purpose, seeking justice, coming to terms with mortality) and in relating to the natural world.
  • 5.4K
  • 14 Oct 2022
Topic Review Peer Reviewed
Mechanics and Mathematics in Ancient Greece
This entry presents an overview on how mechanics in Greece was linked to geometry. In ancient Greece, mechanics was about lifting heavy bodies, and mathematics almost coincided with geometry. Mathematics interconnected with mechanics at least from the 5th century BCE and became dominant in the Hellenistic period. The contributions by thinkers such as Aristotle, Euclid, and Archytas on fundamental problems such as that of the lever are sketched. This entry can be the starting point for a deeper investigation on the connections of the two disciplines through the ages until our present day.
  • 5.4K
  • 13 Apr 2022
Topic Review
Classes of Transposable Elements
Transposable elements (TEs) are mobile genetic elements that constitute a sizeable portion of many eukaryotic genomes. Through their mobility, they represent a major source of genetic variation, and their activation can cause genetic instability and has been linked to aging, cancer and neurodegenerative diseases.
  • 5.4K
  • 23 Sep 2022
Topic Review
Authority
Authority refers to the legitimate power or right to give commands, make decisions, and enforce obedience. It is a social, organizational, or governmental structure that establishes individuals or institutions as having the rightful power to lead, guide, or govern others. Authority is an essential aspect of social order, as it helps maintain stability and facilitates the functioning of institutions, organizations, and societies.
  • 5.4K
  • 25 Jan 2024
Topic Review
New Guinea Highlands
The New Guinea Highlands, also known as the Central Range or Central Cordillera, is a long chain of mountain ranges on the island of New Guinea, including the island's tallest peak, Puncak Jaya 16,024 ft (4,884 m), the highest mountain in Oceania. The range is home to many intermountain river valleys, many of which support thriving agricultural communities. The highlands run generally east-west the length of the island, which is divided politically between Indonesia in the west and Papua New Guinea in the east.
  • 5.4K
  • 09 Nov 2022
Topic Review
Adjustable-Speed Drive
Adjustable speed drive (ASD), also known as variable-speed drive (VSD), describes equipment used to control the speed of machinery. Many industrial processes such as assembly lines must operate at different speeds for different products. Where process conditions demand adjustment of flow from a pump or fan, varying the speed of the drive may save energy compared with other techniques for flow control. Where speeds may be selected from several different pre-set ranges, usually the drive is said to be adjustable speed. If the output speed can be changed without steps over a range, the drive is usually referred to as variable speed. Adjustable and variable speed drives may be purely mechanical (termed variators), electromechanical, hydraulic, or electronic.
  • 5.4K
  • 10 Nov 2022
Topic Review
Late Devonian Extinction
The Late Devonian extinction was one of five major extinction events in the history of life on Earth. A major extinction, the Kellwasser event, occurred at the boundary that marks the beginning of the last phase of the Devonian period, the Famennian faunal stage (the Frasnian–Famennian boundary), about 376–360 million years ago. Overall, 19% of all families and 50% of all genera became extinct. A second, distinct mass extinction, the Hangenberg event, closed the Devonian period. Although it is clear that there was a massive loss of biodiversity in the Late Devonian, the timespan of this event is uncertain, with estimates ranging from 500,000 to 25 million years, extending from the mid-Givetian to the end-Famennian. Nor is it clear whether there were two sharp mass extinctions or a series of smaller extinctions, though the latest research suggests multiple causes and a series of distinct extinction pulses during an interval of some three million years. Some consider the extinction to be as many as seven distinct events, spread over about 25 million years, with notable extinctions at the ends of the Givetian, Frasnian, and Famennian stages. By the Late Devonian, the land had been colonized by plants and insects. In the oceans were massive reefs built by corals and stromatoporoids. Euramerica and Gondwana were beginning to converge into what would become Pangaea. The extinction seems to have only affected marine life. Hard-hit groups include brachiopods, trilobites, and reef-building organisms; the reef-building organisms almost completely disappeared. The causes of these extinctions are unclear. Leading hypotheses include changes in sea level and ocean anoxia, possibly triggered by global cooling or oceanic volcanism. The impact of a comet or another extraterrestrial body has also been suggested, such as the Siljan Ring event in Sweden. Some statistical analysis suggests that the decrease in diversity was caused more by a decrease in speciation than by an increase in extinctions. This might have been caused by invasions of cosmopolitan species, rather than by any single event. Surprisingly, jawed vertebrates seem to have been unaffected by the loss of reefs or other aspects of the Kellwasser event, while agnathans were in decline long before the end of the Frasnian.
  • 5.4K
  • 30 Nov 2022
Topic Review
Solar PV-Hydrogen-PEM Fuel Cell System
The results obtained from the design and analysis of a photovoltaic-hydrogen-PEM fuel cell (PVHPEMFC) hybrid system for Najaf City in Iraq has been presented. The hybrid system consists of photovoltaic arrays coupled with an electrolyzer to produce hydrogen, a PEM fuel cell that converts chemical energy (H2) to electricity, hydrogen storage, a battery storage system, and the load. In this kind of system, all components can be connected electrically in parallel. The voltage of the PV arrays and fuel cell must be high enough to charge the battery, and the voltage of the electrolyzer must be low enough for the battery to power it during periods of low insolation. The designed system model is based on the electrical component models and variable solar radiation data depending on the location.
  • 5.4K
  • 29 Oct 2020
Topic Review
Spray freeze-drying in pharmaceutical products
Pharmaceutical manufacturing is evolving from traditional batch processes to continuous ones. The present review deals with the most recent technologies, based on spray freeze-drying, that can achieve this objective. It provides a comprehensive overview of the physics behind this process and of the most recent equipment design.
  • 5.4K
  • 27 Oct 2020
Topic Review
Law of War
The law of war is the component of international law that regulates the conditions for initiating war (jus ad bellum) and the conduct of warring parties (jus in bello). Laws of war define sovereignty and nationhood, states and territories, occupation, and other critical terms of international law. Among other issues, modern laws of war address the declarations of war, acceptance of surrender and the treatment of prisoners of war; military necessity, along with distinction and proportionality; and the prohibition of certain weapons that may cause unnecessary suffering. The law of war is considered distinct from other bodies of law—such as the domestic law of a particular belligerent to a conflict—which may provide additional legal limits to the conduct or justification of war.
  • 5.4K
  • 08 Oct 2022
Topic Review
The Factors That Influence Food Waste
Food conservation is an issue of global importance. In unstable conditions such as pandemics and wars, clean plate campaigns have been developed to limit food waste around the world. The COVID-19 pandemic threatens global food security and has created an urgent need for food conservation
  • 5.4K
  • 31 May 2022
Topic Review
Bacha Bazi
Bacha bāzī (Dari: بچه بازی‎, lit. "boy play"; from بچه bacheh, "boy", and بازی bazi "play, game") is a slang term in some parts of Afghanistan for a wide variety of activities involving sexual relations between younger adolescent men or boys, who are called dancing boys, and older men. The custom is connected to sexual slavery and child prostitution. In the 21st century, Bacha bazi is reportedly practiced in various parts of Afghanistan. Force and coercion are common, and security officials state they are unable to end such practices because many of the men involved in bacha bazi-related activities are powerful and well-armed warlords. During the Afghan Civil War (1996–2001), bacha bazi carried the death penalty under Taliban law. The practice of dancing boys is illegal under Afghan law, but the laws are seldom enforced against powerful offenders and police have reportedly been complicit in related crimes. A controversy arose after allegations surfaced that U.S. government forces in Afghanistan after the invasion of the country deliberately ignored bacha bazi. The U.S. military responded by claiming the abuse was largely the responsibility of the "local Afghan government". As of 2020, despite international concern, the practice continues.
  • 5.4K
  • 18 Oct 2022
Topic Review
Heteroscedasticity
In statistics, a vector of random variables is heteroscedastic (or heteroskedastic; from Ancient Greek hetero "different" and skedasis "dispersion") if the variability of the random disturbance is different across elements of the vector. Here, variability could be quantified by the variance or any other measure of statistical dispersion. Thus heteroscedasticity is the absence of homoscedasticity. A typical example is the set of observations of income in different cities. The existence of heteroscedasticity is a major concern in regression analysis and the analysis of variance, as it invalidates statistical tests of significance that assume that the modelling errors all have the same variance. While the ordinary least squares estimator is still unbiased in the presence of heteroscedasticity, it is inefficient and generalized least squares should be used instead. Because heteroscedasticity concerns expectations of the second moment of the errors, its presence is referred to as misspecification of the second order. The econometrician Robert Engle was awarded the 2003 Nobel Memorial Prize for Economics for his studies on regression analysis in the presence of heteroscedasticity, which led to his formulation of the autoregressive conditional heteroscedasticity (ARCH) modeling technique.
  • 5.4K
  • 14 Oct 2022
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