Your browser does not fully support modern features. Please upgrade for a smoother experience.
Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort by:
Most Viewed Latest Alphabetical (A-Z) Alphabetical (Z-A)
Filter:
All Topic Review Biography Peer Reviewed Entry Video Entry
Topic Review
Radio Frequency Energy Harvesting System and Technologies
Radio frequency energy harvesting (RF-EH) is a potential technology via the generation of electromagnetic waves. This advanced technology offers the supply of wireless power that is applicable for battery-free devices, which makes it a prospective alternative energy source for future applications.
  • 3.7K
  • 05 Aug 2022
Topic Review
Sonic Hedgehog
Sonic hedgehog is a protein encoded for by the SHH gene. The protein is named after the character Sonic the Hedgehog. This signaling molecule is key in regulating embryonic morphogenesis in all different types of animals. SHH controls organogenesis and the organization of the central nervous system, limbs, digits and many other parts of the body. Sonic hedgehog is a morphogen that patterns the developing embryo using a concentration gradient characterized by the French Flag model. This model has a non-uniform distribution of SHH molecules which governs different cell fates according to concentration. Mutations in this gene can cause holoprosencephaly, a failure of splitting in the cerebral hemispheres, as demonstrated in an experiment using SHH knock-out mice in which the forebrain midline failed to develop and instead only a single fused telencephalic vesicle resulted. Sonic hedgehog still plays a role in differentiation, proliferation, and maintenance of adult tissues. Abnormal activation of SHH signaling in adult tissues has been implicated in various types of cancers including breast, skin, brain, liver, gallbladder and many more.
  • 3.7K
  • 21 Nov 2022
Topic Review
Trewartha Climate Classification
The Trewartha climate classification is a climate classification system first published by American geographer Glenn Thomas Trewartha in 1966. It is a modified version of the Köppen-Geiger system, created to answer some of its deficiencies. The Trewartha system attempts to redefine the middle latitudes to be closer to vegetation zoning and genetic climate systems. It was considered a more true or "real world" reflection of the global climate. The changes were seen as most effective on the large landmasses in Asia and North America, where many areas fall into a single group (C) in the Köppen-Geiger system. For example, under the standard Köppen system, Washington (state) and Oregon are classed into the same climate zone (Csb) as Southern California, even though the two regions have strikingly different weather and vegetation. Another example was classifying cities like London in the same climate group (C) as Brisbane or New Orleans, despite great differences in seasonal temperatures and native plant life.
  • 3.7K
  • 29 Nov 2022
Topic Review
Power Posing
Power posing is a controversial self-improvement technique or "life hack" in which people stand in a posture that they mentally associate with being powerful, in the hope of feeling and behaving more assertively. Though the underlying science is strongly disputed, its promoters continue to argue that people can foster positive life changes simply by assuming a "powerful" or "expansive" posture for a few minutes before an interaction in which confidence is needed. One popular image of the technique in practice is that of candidates "lock[ing] themselves in bathroom stalls before job interviews to make victory V's with their arms." Power posing was first suggested in a 2010 paper by Dana R. Carney, Amy Cuddy, and Andy Yap in the journal Psychological Science, and came to prominence through a popular TED talk by Cuddy in 2012. However, in 2015 several researchers began reporting that the effect could not be replicated, and, in 2016, Carney issued a statement abandoning the theory. Cuddy, however, continued her research, claiming to have evidence that posture feedback can at least make people feel more powerful. Today, power posing is often cited as an example of the replication crisis in the sciences.
  • 3.7K
  • 01 Dec 2022
Topic Review
Geopolymers as Construction Materials
Utilising geopolymer as a construction material has gained institutional and commercial interest over the past decade, due to its favourable emissions profile as an alternative to carbon-intensive Ordinary Portland Cement-based concrete, which currently accounts for around 7% of global carbon emissions.
  • 3.7K
  • 11 May 2021
Topic Review
Fabrication Techniques Using Myco-Materials
Within Euro-centric traditions of architecture, the significance of a building is often tied to its permanence. The Pantheon in Rome, for example, is a nearly 2000-year-old cementitious dome structure, whose resilience to time elevates it to a monumental status. Notwithstanding the significance of cultural and economic factors associated with the need for permanent buildings and structures, there is a doubt on whether all buildings should be assembled with the goal of being permanent. Globally, the lifespans of buildings are rapidly decreasing. The average lifespan of buildings in China was reported to be 34 years, and 25 years for residential buildings in Japan. To great detriment, buildings are more than ever being demolished prematurely and yet, use materials that are manufactured with energy-intensive processes and are expensive or impractical to recycle. In the United States alone, the Environmental Protection Agency (EPA) reported there was 600 million tons of construction and demolition waste generated in 2018. Structural materials, including wood, and architectural metals, such as steel, copper, and brass, are valuable commodities that can be reused and recycled. However, in present-day architectural assemblies, these materials nearly ubiquitously inter-face with expanded foams, plastics, and resins, sometimes in irreversible composites. For example, wood is widely treated with synthetic resins and glues to increase its resistance to decay or structural performance.
  • 3.7K
  • 28 Sep 2022
Topic Review
Metabolic Equivalent
The Metabolic Equivalent of Task (MET), or simply metabolic equivalent, is a physiological measure expressing the energy cost of physical activities and is defined as the ratio of metabolic rate (and therefore the rate of energy consumption) during a specific physical activity to a reference metabolic rate, set by convention to 3.5 ml O2·kg−1·min−1 or approximately: [math]\displaystyle{ \text{1 MET}\ = 1 \dfrac{\text{kcal}}{\text{kg}*\text{h}}\ = 4.184 \dfrac{\text{kJ}}{\text{kg}*\text{h}} = 1.1622222... \dfrac{\text{W}}{\text{kg}} }[/math] Still another definition of 1 MET is 58.2 W/m2 (18.4 Btu/h·ft2), which is equal to the rate of energy produced per unit surface area of an average person seated at rest. The surface area of an average person is 1.8 m2 (19 ft2). Metabolic rate is usually expressed in terms of unit area of the total body surface (ANSI/ASHRAE Standard 55). Originally, 1 MET was considered as the Resting Metabolic Rate (RMR) obtained during quiet sitting. MET values of activities range from 0.9 (sleeping) to 23 (running at 22.5 km/h or a 4:17 mile pace). Although the RMR of any person may deviate from the reference value, MET can be thought of as an index of the intensity of activities: for example, an activity with a MET value of 2, such as walking at a slow pace (e.g., 3 km/h) would require twice the energy that an average person consumes at rest (e.g., sitting quietly). MET is used as a means of expressing the intensity and energy expenditure of activities in a way comparable among persons of different weight. Actual energy expenditure (e.g., in calories or joules) during an activity depends on the person's body mass; therefore, the energy cost of the same activity will be different for persons of different weight. However, since the RMR is also dependent on body mass in a similar way, it is assumed that the ratio of this energy cost to the RMR of each person will remain more or less stable for the specific activity and thus independent of each person's weight. The 1 MET reference value of 1 kcal·kg−1·h−1, is used by convention and refers to a typical metabolism at rest of an "average" individual. It is not an approximation of Basal Metabolic Rate (BMR), which is the minimum metabolic rate obtained under specified conditions. This is illustrated by sleeping having a MET of 0.9, while an individual's normal sleeping metabolism may be greater than the BMR.
  • 3.7K
  • 14 Oct 2022
Topic Review
Usul Fiqh in Ja'fari School
Ja'fari principles (Persian: علم اصول در مکتب جعفری‎) refers to regulations, history and eminent persons and scholars during the development of Shia's Principles of Islamic jurisprudence.
  • 3.7K
  • 28 Oct 2022
Topic Review
Types of Pipeline Anomalies
Pipelines are considered the most efficient way to transport oil and gas resources. However, this advantage of pipelines may be lost if pipeline integrity is not ensured. Geometric deformations, metal losses, and crack-type anomalies caused by various reasons in the pipeline threaten the integrity of the pipeline. Therefore, it is important to examine the causes of occurrence, hazard potentials, and management methods of pipeline anomalies as part of pipeline integrity management. 
  • 3.7K
  • 27 Apr 2023
Topic Review
Glucose Uptake by Skeletal Muscle
Skeletal muscle is the primary tissue for maintaining glucose homeostasis through glucose uptake via insulin-dependent and -independent mechanisms. Skeletal muscle is also responsive to exercise-meditated glucose transport, and as such, exercise is a cornerstone for glucose management in people with type 2 diabetes.
  • 3.7K
  • 07 Mar 2022
Topic Review
Gall Stone Dissolving Plants
Medicinal plants have been known for thousands of years and are highly esteemed throughout the world as a rich source of therapeutic agents for the prevention and cure of diseases. There is large number of population suffers from gall stone. Gall stones problem is now being increased significantly due to changes in living style and conditions i.e. industrialization and malnutrition. Medicinal plants are used from centuries due to its, cultural acceptability, efficacy, safety and lesser side effects as compared to synthetic drugs.
  • 3.7K
  • 15 Aug 2022
Topic Review
Terma (Religion)
Terma (Tibetan: གཏེར་མ་, Wylie: gter ma; "hidden treasure") are various forms of hidden teachings that are key to Vajrayana or Tibetan Buddhist and Bon religious traditions. The belief is that these teachings were originally esoterically hidden by various adepts such as Padmasambhava and dakini such as Yeshe Tsogyal (consorts) during the 8th century, for future discovery at auspicious times by other adepts, who are known as tertöns. As such, terma represent a tradition of continuous revelation in Vajrayana or Tibetan Buddhism. Termas are a part of tantric literature.
  • 3.7K
  • 26 Oct 2022
Topic Review Peer Reviewed
Bagnoli Urban Regeneration through Phytoremediation
The Bagnolidistrict in Naples has needed urban redevelopmentfor many years. The area is not only affected by pollution caused by many industries but also by environmental pollutants, according togeognostic surveys that have found numerous contaminantsin the subsoil and water.Currently, the combination of an urban rehabilitation processwith the phytodepuration technique may represent a successful idea for obtaining bothurban regenerationand environmental remediation. Phytoremediation, a biologically based technology, has attracted the attention of both thepublic and scientists as a low-cost alternative for soil requalification. The use of plants as well as the microorganisms present in their root systems plays an important role in the ecological engineering field in controlling and reducing pollutants present in theair, water and soil.The result is efficient, sustainable and cost-effective environmental recovery compared to conventional chemical–physical techniques. In this way, not only the environmental recovery of SIN Bagnoli-Corogliocan be obtained, but also the regeneration of its landscape.
  • 3.7K
  • 27 Apr 2022
Topic Review
Adenosine Deaminase
Adenosine deaminase (ADA, EC 3.5.4.4) - the enzyme engaged in purine metabolism that irreversibly converts adenosine or 2′deoxyadenosine to inosine or 2′deoxyinosine, respectively. In human tissues, it occurs as two isoenzymes: ADA1 and ADA2. ADA1 constitutes the majority of ADA activity and it is present in virtually all tissues, while ADA2 has been found with ADA1 only in monocytes/macrophages. Both ADA isoenzymes are present in cytosolic form, soluble fraction that can be located away from the originating cell, or as ecto-enzymes binding to the cell surface by dedicated proteins. Intracellularly, ADA plays a significant role counteracting high concentrations of 2'deoxyadenosine. When intracellular ADA activity is lowered, e.g. during severe combined immunodeficiency disease (SCID), 2′deoxyadenosine accumulates and is converted to 2′-deoxyadenosine-5′-triphosphate (dATP), which inhibits ribonucleotide reductase (RNR), a crucial enzyme in DNA synthesis that follows disrupted T-cell development. Intracellular concentration of adenosine, the second substrate for ADA, is maintained inside the cell on the low level by adenosine kinase with Km value ~ 1 µM. Under conditions of low energy charge, adenosine-5′-monophosphate (AMP) that originates from adenosine-5′-triphosphate (ATP) degradation, is rapidly transformed to adenosine, which is not immediately deaminated to inosine due to high Km of ADA (25–100 µM). This results in temporary accumulation of adenosine that is vigorously exported out the cell via equilibrative nucleoside transporters (ENTs). Therefore, transmembrane adenosine transport, together with the activities of ecto-ADA and soluble ADA are important regulators of extracellular adenosine concentration. Except enzymatic function, ecto-ADA plays a significant extra-enzymatic role in the interactions between cells that expressed ADA-anchoring proteins on their surfaces. This co-stimulatory and cell-to-cell connecting actions along with its activity regulate many cellular processes related to proliferation and differentiation, which affect pathological conditions associated with cardiovascular diseases such as endothelial activation and dysfunction, inflammation, myocardial ischemia-reperfusion injury, or coagulation disorders. Since these pathologies are associated with ADA overexpression, the inhibition of its activity as well as binding to the surface proteins exhibit an attractive therapeutic potential in cardiovascular diseases.
  • 3.7K
  • 30 Oct 2020
Topic Review
Class D Audio Power Amplifier
Class D power amplifiers, one of the most critical devices for application in sound systems, face severe challenges due to the increasing requirement of smartphones, digital television, digital sound, and other terminals. The audio power amplifier has developed from a transistor amplifier to a field-effect tube amplifier, and digital amplifiers have made significant progress in circuit technology, components, and ideological understanding. The stumbling blocks for a successful power amplifier are low power efficiency and a high distortion rate.
  • 3.7K
  • 01 Nov 2022
Topic Review
European Hedgehog (Erinaceus Europaeus): Sentinel
Erinaceus europaeus is a cosmopolitan mammalian species broadly distributed in Europe, from natural to suburban areas. Due to its ecological role and susceptibility to distinct zoonotic agents, E. europaeus could be a suitable sentinel candidate for many global problems that negatively affect human and animal health. Hedgehogs can work as bioindicators to environmental contamination and can be hosts for multiple tickborne zoonotic agents. 
  • 3.7K
  • 04 Jul 2022
Topic Review
Grid-Forming Converters and Power System Stability
Historically, the power system has relied on synchronous generators (SGs) to provide inertia and maintain grid stability. However, because of the increased integration of power-electronics-interfaced renewable energy sources, the grid’s stability has been challenged in the last decade due to a lack of inertia. Currently, the system predominantly uses grid-following (GFL) converters, built on the assumption that inertial sources regulate the system stability. Such an assumption does not hold for the low-inertia grids of the future. Grid-forming (GFM) converters, which mimic the traditional synchronous machinery’s functionalities, have been identified as a potential solution to support the low-inertia grids. The performance analysis of GFM converters for small-signal instability can be found in the literature, but large-signal instability is still an open research question. Moreover, various topologies and configurations of GFM converters have been proposed. Still, no comparative study combining all GFC configurations from the perspective of large-signal stability issues can be found. This research combines and compares all the existing GFM control schemes from the perspective of large-signal stability issues to pave the way for future research and development of GFM converters for large-signal stability analysis and stabilization of the future low-inertia grids. 
  • 3.7K
  • 19 Jul 2022
Topic Review
Merchant Vessel
A merchant vessel, trading vessel or merchantman is a boat or ship that transports cargo or carries passengers for hire. This excludes pleasure craft that do not carry passengers for hire; warships are also excluded. They come in a myriad of sizes and shapes, from twenty-foot inflatable dive boats in Hawaii, to 5,000 passenger casino vessels on the Mississippi River, to tugboats plying New York Harbor, to 1,000 foot oil tankers and container ships at major ports, to a passenger carrying submarine in the U.S. Virgin Islands. Most countries of the world operate fleets of merchant ships. However, due to the high costs of operations, today these fleets are in many cases sailing under the flags of nations that specialize in providing manpower and services at favourable terms. Such flags are known as "flags of convenience". Currently, Liberia and Panama are particularly favoured. Ownership of the vessels can be by any country, however. The Greek-owned fleet is the largest in the world. Today, the Greek fleet accounts for some 16 per cent of the world’s tonnage; this makes it currently the largest single international merchant fleet in the world, albeit not the largest in history. During wars, merchant ships may be used as auxiliaries to the navies of their respective countries, and are called upon to deliver military personnel and materiel.
  • 3.7K
  • 25 Oct 2022
Topic Review
Land Surface Model
Land Surface Models (LSMs) are important components of the climate models, which help to capture the water, energy, and momentum exchange between the land surface and the atmosphere, providing lower boundary conditions to the atmospheric models.
  • 3.7K
  • 02 Apr 2021
Topic Review
Acinar Cells for Pancreatic Cancer
The carcinogenesis of pancreatic ductal adenocarcinoma (PDA) progresses according to multi-step evolution, whereby the disease acquires increasingly aggressive pathological features. Lineage-tracing experiments demonstrated that pancreatic cancerous lesions originate from acinar cells, a highly specialized cell type in the pancreatic epithelium. Acinar cells are polarized, pyramidal-shaped cells containing numerous acidophilic granules near the apical side. Those granules contain inactive proteases, which are activated and released into the tubular network upon activation. Primary acinar cells can survive in vitro as organoid-like 3D spheroids, which can transdifferentiate into cells with a clear ductal morphology in response to different cell- and non-cell-autonomous stimuli.This event, termed acinar-to-ductal metaplasia, recapitulates the histological and molecular features of disease initiation.
  • 3.7K
  • 24 Sep 2020
  • Page
  • of
  • 2794
Featured Entry Collections
>>

Featured Reprints

>>
Encyclopedia of Digital Society, Industry 5.0 and Smart City
Encyclopedia of Engineering
Encyclopedia of Social Sciences
Encyclopedia of Medieval Royal Iconography
Academic Video Service
Feedback

Quick Survey

Encyclopedia MDPI is conducting a targeted survey to identify the specific barriers hindering efficient research. We invite you to spend 3 minutes defining the priorities for our next generation of structured knowledge tools.
Take Survey