Search | Encyclopedia MDPI

Your browser does not fully support modern features. Please upgrade for a smoother experience.

Subject:

Sort by:

Most Viewed Latest Alphabetical (A-Z) Alphabetical (Z-A)

Filter:

All Topic Review Biography Peer Reviewed Entry Video Entry

Topic Review

Foreign Influences on Pompeii

Several non-native societies had an influence on Ancient Pompeian culture. Historians’ interpretation of artefacts, preserved by the Eruption of Mount Vesuvius in 79, identify that such foreign influences came largely from Ancient Greece and Hellenistic cultures of the Eastern Mediterranean, including Egypt. Greek influences were transmitted to Pompeii via the Greek colonies in Magna Graecia (Southern Italy), which were formed in the 8th century BC. Hellenistic influences originated from Roman commerce, and later conquest of Egypt from the 2nd century BC. Specifically, these cultures contributed to the development of Pompeii’s art, architecture and religious spheres. For instance, Greek influences can be identified in the Alexander Mosaic, horse-shoe shaped theatres and Pompeii’s adoption of the Greek pantheon of gods. Examples of Egyptian influences can be found in the Nile Mosaic, garden art in the Villa of Julia Felix and the Cult of Isis.

8.4K
11 Oct 2022

Topic Review

Parental Involvement

Parental involvement is seen as an important strategy for the advancement of the quality of education. The ultimate objective of this is to expand the academic and social capacities of students, especially those of disadvantaged backgrounds determined by ethnic minority origin and low socio-economic status. In this contribution, various forms of both parental and school-initiated involvement will be described. In addition, results of studies into the effectiveness of parental involvement will be presented.

8.4K
15 Nov 2021

Topic Review

Segmentation in biology is the division of some animal and plant body plans into a series of repetitive segments. This article focuses on the segmentation of animal body plans, specifically using the examples of the taxa Arthropoda, Chordata, and Annelida. These three groups form segments by using a "growth zone" to direct and define the segments. While all three have a generally segmented body plan and use a growth zone, they use different mechanisms for generating this patterning. Even within these groups, different organisms have different mechanisms for segmenting the body. Segmentation of the body plan is important for allowing free movement and development of certain body parts. It also allows for regeneration in specific individuals.

8.4K
29 Sep 2022

Topic Review

Ray-Finned Fish

Actinopterygii (/ˌæktɪnɒptəˈrɪdʒiaɪ/; from actino- 'having rays', and grc πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fishes, is a clade (traditionally class or subclass) of the bony fishes. They comprise over 50% of living vertebrate species. The ray-finned fishes are so-called because their fins are webs of skin supported by bony or horny spines (rays), as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii (lobe-finned fish). These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton (e.g., pelvic and pectoral girdles). By species count, actinopterygians dominate the vertebrates, and they comprise nearly 99% of the over 30,000 species of fish. They are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from Paedocypris, at 8 mm (0.3 in), to the massive ocean sunfish, at 2,300 kg (5,070 lb), and the long-bodied oarfish, at 11 m (36 ft). The vast majority of Actinopterygii (~99%) are teleosts.

8.4K
29 Nov 2022

Topic Review

SpaceX Dragon 2

The SpaceX Dragon 2 is a class of reusable spacecraft developed and manufactured by American aerospace manufacturer SpaceX as the successor to the Dragon cargo spacecraft. It has two variants: Crew Dragon, a human-rated capsule capable of ferrying up to seven astronauts, and Cargo Dragon, an updated replacement for the original Dragon spacecraft. The spacecraft launches atop a Falcon 9 Block 5 rocket and returns to Earth via an ocean splashdown. Unlike its predecessor, the spacecraft can dock itself to the ISS instead of being berthed. Crew Dragon is equipped with an integrated launch escape system (LES) capable of accelerating the vehicle away from the rocket in an emergency at 11.8 m/s2, accomplished by using a set of four side-mounted thruster pods with two SuperDraco engines each. The spacecraft features redesigned solar arrays and a modified outer mold line compared to the original Dragon, and possess new flight computers and avionics. As of March 2020, four Dragon 2 spacecraft have been manufactured (not counting structural test articles that were never airborne). Crew Dragon serves as one of two spacecraft that is expected to transport crews to and from the International Space Station (ISS) under NASA's Commercial Crew Program, the other being the Boeing CST-100 Starliner. It is also expected to be used in flights by American space tourism company Space Adventures and to shuttle tourists to and from Axiom Space's planned space station. Crew Dragon's first non-piloted test flight occurred in March 2019, and its first crewed flight – with astronauts Robert Behnken and Douglas Hurley – occurred in May 2020. This test flight marked the first time a private company launched a crewed orbital spacecraft. Cargo Dragon is expected to supply cargo to the ISS under a Commercial Resupply Services-2 contract with NASA, along with Northrop Grumman Innovation Systems' Cygnus spacecraft and Sierra Nevada Corporation's Dream Chaser spacecraft. The first flight of the Cargo Dragon is planned to launch in October 2020.

8.4K
26 Oct 2022

Topic Review Peer Reviewed

Natural Disasters: Origins, Impacts, Management

Natural hazards are processes that serve as triggers for natural disasters. Natural hazards can be classified into six categories. Geophysical or geological hazards relate to movement in solid earth. Their examples include earthquakes and volcanic activity. Hydrological hazards relate to the movement of water and include floods, landslides, and wave action. Meteorological hazards are storms, extreme temperatures, and fog. Climatological hazards are increasingly related to climate change and include droughts and wildfires. Biological hazards are caused by exposure to living organisms and/or their toxic substances. The COVID-19 virus is an example of a biological hazard. Extraterrestrial hazards are caused by asteroids, meteoroids, and comets as they pass near earth or strike earth. In addition to local damage, they can change earth inter planetary conditions that can affect the Earth’s magnetosphere, ionosphere, and thermosphere. This entry presents an overview of origins, impacts, and management of natural disasters. It describes processes that have potential to cause natural disasters. It outlines a brief history of impacts of natural hazards on the human built environment and the common techniques adopted for natural disaster preparedness. It also lays out challenges in dealing with disasters caused by natural hazards and points to new directions in warding off the adverse impact of such disasters.

8.4K
13 Apr 2022

Topic Review

Transparency for Architecture

Rowe and Slutzky proposed two types of transparency in architecture in the essay, “Transparency: Literal and Phenomenal”. They divided transparency into literal, meaning the material conditions of glass, and phenomenal, as derived from Cubist paintings. “literal transparency” describes the material quality of being see-through, and phenomenal transparency describes the perceptual attributes that allow the mind to discern the underlying governing concepts or spatial concepts. Through their idea of “phenomenal transparency”, they primarily investigated the relationship of visual perceptions using the human eye with superimposed two-dimensional visions of architectural space and the world.

8.4K
27 Aug 2021

Topic Review

The platypus (Ornithorhynchus anatinus), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or monotypic taxon of its family (Ornithorhynchidae) and genus (Ornithorhynchus), though a number of related species appear in the fossil record. Together with the four species of echidna, it is one of the five extant species of monotremes, mammals that lay eggs instead of giving birth to live young. Like other monotremes, it senses prey through electrolocation. It is one of the few species of venomous mammals, as the male platypus has a spur on the hind foot that delivers a venom, capable of causing severe pain to humans. The unusual appearance of this egg-laying, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered it, and the first scientists to examine a preserved platypus body (in 1799) judged it a fake, made of several animals sewn together. The unique features of the platypus make it an important subject in the study of evolutionary biology, and a recognisable and iconic symbol of Australia . It is culturally significant to several Aboriginal peoples of Australia, who also used to hunt the animal for food. It has appeared as a mascot at national events and features on the reverse of the Australian twenty-cent coin, and the platypus is the animal emblem of the state of New South Wales. Until the early 20th century, humans hunted the platypus for its fur, but it is now protected throughout its range. Although captive-breeding programs have had only limited success, and the platypus is vulnerable to the effects of pollution, it is not under any immediate threat. (As of 2020), the platypus is a legally protected species in all states where it occurs. It is listed as an endangered species in South Australia and Victoria and has been recommended for listing in New South Wales. The species is classified as a near-threatened species by the IUCN, but a November 2020 report has recommended that it is upgraded to threatened species under the federal EPBC Act, due to habitat destruction and declining numbers in all states.

8.4K
18 Nov 2022

Topic Review

Left-Wing Market Anarchism

Left-wing market anarchism is a strand of free-market anarchism and an individualist anarchist, left-libertarian and libertarian socialist political philosophy and market socialist economic theory stressing the value of radically free markets, termed freed markets to distinguish them from the common conception which these libertarians believe to be riddled with statist and capitalist privileges. Proponents of this approach distinguish themselves from right-libertarians and strongly affirm the classical liberal ideas of self-ownership and free markets while maintaining that taken to their logical conclusions these ideas support anti-capitalist, anti-corporatist, anti-hierarchical and pro-labor positions in economics; anti-imperialism in foreign policy; and thoroughly radical views regarding socio-cultural issues. Key theorists in this area include contemporary scholars such as Kevin Carson, Gary Chartier, Charles W. Johnson, Roderick T. Long, Chris Matthew Sciabarra, Ryan Neugebauer, Sheldon Richman and Brad Spangler. The genealogy of left-wing market anarchism, sometimes labeled market-oriented or free-market left-libertarianism, overlaps to a significant degree with that of Steiner–Vallentyne left-libertarianism as the roots of that tradition are sketched in the book The Origins of Left-Libertarianism. Carson–Long-style left-libertarianism is rooted in 19th-century mutualism and in the work of figures such as Thomas Hodgskin, French Liberal School thinkers such as Gustave de Molinari and American individualist anarchists such as Benjamin Tucker and Lysander Spooner, among others. Several left-wing market anarchists who come from the left-Rothbardian school or tradition cite Murray Rothbard's homestead principle with approval to support worker cooperatives. While with notable exceptions libertarians in the United States after the heyday of individualist anarchism tended to ally with the political right, relationships between such libertarians and the New Left thrived in the 1960s, laying the groundwork for modern left-wing market anarchism. Left-wing market anarchism identifies with left-libertarianism, a position which names several related yet distinct approaches to politics, society, culture and political and social theory, stressing both individual freedom and social justice. Unlike right-libertarians, left-libertarians believe that neither claiming nor mixing one's labor with natural resources is enough to generate full private property rights and maintain that all natural resources such as land, oil and gold ought to be held in some egalitarian manner, either unowned or owned collectively. Those left-libertarians who support private property do so under different property norms and theories, or under the condition that recompense is offered to the local or global community.

8.4K
30 Nov 2022

Topic Review

Collective Consciousness

Collective consciousness, a concept introduced by sociologist Emile Durkheim, refers to the shared beliefs, values, norms, and symbols that unite members of a society and shape their collective identity. It represents the collective understanding of social reality, guiding individuals' behaviors, interactions, and perceptions within a community. Collective consciousness fosters social cohesion, solidarity, and integration by providing a common framework for interpreting the world and coordinating social action.

8.4K
08 Feb 2024

Topic Review

Silicon photonics has drawn increasing attention since recent decades and is promising to act as a key technology for future daily applications due to its various merits including ultra-low cost, high integration density owing to the high refractive index of silicon and compatibility with current semiconductor fabrication process. Optical interconnects is an important issue in silicon photonic integrated circuits to transmit light and fiber-to-chip optical interconnects is vital in application scenarios like data centers and optical transmission systems. There are mainly two categories of fiber-to-chip optical coupling, that is off-plane coupling and in-plane coupling. Grating couplers work under the former category while edge couplers function as in-plane coupling. In this paper, we mainly focus on edge couplers in silicon photonic integrated circuits. We deliver an introduction to the research background, operation mechanism and design principles of silicon photonic edge couplers. The state-of-the-art of edge couplers is reviewed according to different configurations as to the device structure, identifying the performance, fabrication feasibility and applications. In addition, a brief comparison between edge couplers and grating couplers is conducted. Packaging issue is also discussed and several prospective techniques for further improvements of edge couplers are proposed.

8.4K
27 Oct 2020

Topic Review

The concept of the "iron cage," introduced by sociologist Max Weber, metaphorically describes the rationalization and bureaucratization of modern society, wherein individuals become trapped by rigid systems of rules, regulations, and rationalized institutions. It signifies the loss of individual autonomy and creativity as bureaucratic structures increasingly dominate social life, constraining human agency within the confines of rationalized systems.

8.4K
08 Feb 2024

Topic Review

Estimation of Maize Yield Per Harvest Area

Maize (Zea mays L.) is one of the most important annual cereal crops in the world, providing a staple food, and being used as source of income for many populations in developing countries. Different methods can be used for estimating maize yields depending on the purpose for which the crop was produced. The estimation of yield can be calculated using kernel weight at harvest, plot area harvested, plant density, and moisture content of grain at harvest.

8.4K
10 Jan 2022

Topic Review

Principles of SERS

SERS (Surface-enhanced Raman spectroscopy) is based on the amplification of the Raman response of an analyte interacting with the surface plasmon of metals such as Au, Ag, or Cu; in some cases, the response results enough to achieve the single–molecule detection

8.4K
21 Apr 2021

Topic Review

Addiction and Spending in Gacha Games

Gacha games are the most dominant games on the mobile market. These are free-to-play games with a lottery-like system, where the user pays with in-game currency to enter a draw in order to obtain the character or item they want. If a player does not obtain what he hoped for, there is the option of paying with his own money for more draws, and this is the main way to monetize the Gacha game.

8.4K
21 Jul 2023

Topic Review

Green Monopropellants

Green propellants are usually defined as low-hazard, low-toxicity, environmentally friendly propellants that are considered safe during various phases of spacecraft development, launch, and operations. Such propellants provide safe handling and storability when compared to conventional toxic propellants such as hydrazine and its derivatives that require special handling protocols and adhering to strict safety measurements that, in addition to others, include using Self-Contained Atmospheric Protective Ensemble (SCAPE) suits. Due to their favorable characteristics, green propellants demonstrate higher commercial value by being able to cut costs related to transportation, storage, handling, and further reduces ground operations time. Recently, a more specified definition has been noted by Mayer et al. (2018) [3], based on the Acute Toxicity Classification (ATC) by the Global Harmonized System of classification and labeling of chemicals (GHS) [6], which denotes that propellants possessing ATC levels of three and safer are considered as green propellants. ATC levels are typically categorized on a 1:5 scale where level one denotes the most toxic class and level five is considered the least toxic class. Moreover, a controversial topic arises when referring to some modern green propellants, whether to address them by the term “monopropellants” or by more specific terms including (premixed propellants, fuel blends, or mixtures). Monopropellants are fundamentally defined as propellants consisting of chemical compounds (for example N2H4), which release energy through exothermic chemical decomposition. Since the evolution of liquid gun propellants based on HAN compound and other nitrate salts aqueous solutions, the term “monopropellants” was used to describe such premixed formulations. As widely used in literature and industry, some modern green propellants, for instance the Energetic Ionic Liquids (EILs), are undoubtedly classified and described as “monopropellants.” Basically, it can be interpreted from the previous that a "green monopropellant" may be defined as: "A low-hazard, low-toxicity, and safe-to handle propellant that is stored in a single tank and is able to decompose from its storage state by the help of a catalyst or other ignition method, such as thermal or electric ignition, can be considered a “green monopropellant” as long as it does not require another separately stored propellant for decomposition."

8.4K
28 Sep 2021

Topic Review

Seaports are well known as the medium that has evolved into the central link between sea and land for complex marine activities. The growth in maritime logistics particularly necessitates a large volume of energy supply in order to maintain the operation of sea trade, resulting in an imbalance between generation and demand sides. Future projections for three major concerns show an increase in load demand, cost of operation, and environmental issues. The involvement of a variety of heavy loads such as all-electric ships, cranes, cold ironing, and buildings infrastructure renders it a complicated arrangement task in several aspects, which necessitates further research and leaves space for improvement.

8.3K
06 Dec 2021

Topic Review

eCommerce and Small and Medium Enterprises

The rise of smaller businesses has been an essential trend since the 1990s, when they became engines for economic development. Now, Small and Medium Enterprises (SMEs) across the world are increasingly relying on eCommerce channels to create and capture value. The growth in eCommerce operations is being fueled by several global and technological developments. eCommerce allows SMEs to benefit from globalization by expanding their ability to access customers around the world and across customer demographics and categories. This emergence of a new range of markets has made strategic flexibility essential for SMEs, as such expansion requires a consistent rethinking and adapting to continually changing dynamics in a global environment.

8.3K
07 May 2022

Topic Review

Grievance Studies Affair

The Grievance Studies affair, also referred to as "hoax" or the "Sokal Squared" scandal (in reference to a similar 1996 hoax), was an attempt by a team of three authors (James A. Lindsay, Peter Boghossian, and Helen Pluckrose) to create bogus academic papers and submit them to academic journals with the intent of testing the strength of the editorial and peer review process. The hoax began in 2017 and ended in 2018. The authors targeted the academic areas of cultural, race, gender, fat, and sexuality studies in which they believed poor science was undermining the field, which they collectively refer to as "grievance studies". The project was halted early after one of the papers was criticized on social media, then its authenticity questioned on Campus Reform, and finally the hoax being more broadly exposed by the Wall Street Journal in 2018 alongside a YouTube video created and released by documentary filmmaker Mike Nayna. By the time of the reveal, four of their 20 papers had been published, one had won an award, three had been accepted but not yet published, six had been rejected, and seven were still under review.

8.3K
08 Nov 2022

Topic Review

Fly ash or coal fly ash causes major global pollution in the form of solid waste and is classified as a “hazardous waste”, which is a by-product of thermal power plants produced during electricity production. Si, Al, Fe Ca, and Mg alone form more than 85% of the chemical compounds and glasses of most fly ashes. Fly ash has a chemical composition of 70–90%, as well as glasses of ferrous, alumina, silica, and CaO. Therefore, fly ash could act as a reliable and alternative source for ferrous, alumina, and silica. The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than the biological approaches, but the bio-based approaches are more environmentally friendly. Fly ash can also be used for the synthesis of zeolites by NaOH treatment of variable types, as fly ash is rich in alumino-silicates. The present review work deals with the recent advances in the field of the recovery and synthesis of ferrous, alumina, and silica micro and nanoparticles from fly ash.

8.3K
06 Apr 2021

Page
of
2727

Featured Entry Collections

>>

Featured Reprints

>>

Encyclopedia of Digital Society, Industry 5.0 and Smart City

Encyclopedia of Digital Society, Industry 5.0 and Smart City
Chief Editor: Sandro Serpa

Encyclopedia of Engineering

Encyclopedia of Social Sciences

Encyclopedia of Social Sciences
Chief Editor: Kum Fai Yuen

Encyclopedia of Medieval Royal Iconography

Encyclopedia of Medieval Royal Iconography
Published Version (2022) >>
Chief Editor: Mirko Vagnoni

Academic Video Service

Feedback

Top