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Topic Review
Exercise influence on calcium-phosphorous metabolism
Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the e ects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise.
  • 3.1K
  • 26 Aug 2020
Biography
Saint Sava
Saint Sava (Serbian: Свети Сава / Sveti Sava, pronounced [sʋɛ̂ːtiː sǎːʋa], 1174 – 14 January 1236), known as The Enlightener, was a Serbian prince and Orthodox monk, the first Archbishop of the autocephalous Serbian Church, the founder of Serbian law, and a diplomat. Sava, born as Rastko (Serbian Cyrillic: Растко), was the youngest son of Serbian Grand Prince Stefan Nem
  • 3.1K
  • 16 Nov 2022
Topic Review
Miscanthus X Giganteus
Miscanthus × giganteus, also known as the giant miscanthus, is a sterile hybrid of Miscanthus sinensis and Miscanthus sacchariflorus. It is a perennial grass with bamboo-like stems that can grow to heights of 3–4 metres (13 ft) in one season (from the third season onwards). Just like Pennisetum purpureum, Arundo donax and Saccharum ravennae, it is also called elephant grass. Miscanthus × giganteus' perennial nature, its ability to grow on marginal land, its water efficiency, non-invasiveness, low fertilizer needs, significant carbon sequestration and high yield have sparked significant interest among researchers, with some arguing that it has "ideal" energy crop properties. Some argue that it can provide negative emissions, while others highlight its water cleaning and soil enhancing qualities. There are practical and economic challenges related to its use in the existing, fossil based combustion infrastructure, however. Torrefaction and other fuel upgrading techniques are being explored as countermeasures to this problem.
  • 3.1K
  • 01 Dec 2022
Topic Review
Corroles and Hexaphyrins
Recent developments in the synthesis of corroles and hexaphyrins are reviewed, highlighting their potential application in photodynamic therapy.
  • 3.1K
  • 24 Aug 2020
Topic Review
IP Code
The IP Code, International Protection Marking, IEC standard 60529, sometimes interpreted as Ingress Protection Marking, classifies and rates the degree of protection provided against intrusion (body parts such as hands and fingers), dust, accidental contact, and water by mechanical casings and electrical enclosures. It is published by the International Electrotechnical Commission (IEC). The equivalent European standard is EN 60529. The standard aims to provide users more detailed information than vague marketing terms such as waterproof. For example, a cellular phone rated at IP68 is "dust resistant" and can be "immersed in 1.5 meters of freshwater for up to 30 minutes". Similarly, an electrical socket rated IP22 is protected against insertion of fingers and will not be damaged or become unsafe during a specified test in which it is exposed to vertically or nearly vertically dripping water. IP22 or IP2X are typical minimum requirements for the design of electrical accessories for indoor use. The digits indicate conformity with the conditions summarized in the tables below. The digit 0 is used where no protection is provided. The digit is replaced with the letter X when insufficient data has been gathered to assign a protection level. There are no hyphens in a genuine IP code. IPX-8 (for example) is thus an invalid IP code. This page contains a combination of IEC 60529 (also EN 60529) and other standards, such as ISO 20653. The original documents are available for purchase, and have important and specific requirements that cannot be fully reprinted due to copyright restrictions. This often includes drawings specifying the required test equipment, such as the shape of water nozzles used for water jet testing. Additional standards are often referenced that may contain important information. One must refer to the latest revision of the required standard when conducting tests for agency certification.
  • 3.1K
  • 16 Nov 2022
Topic Review
Passive Downdraft Cooling Systems in Buildings
Energy demand for active mechanical space cooling is projected to double by 2050. Wider adoption of passive cooling systems can help reduce demand.
  • 3.1K
  • 16 Jun 2023
Topic Review
Conductive Fibers
As one of the most impressive materials for wearable sensors, conductive fibers can be made from a variety of raw sources via diverse preparation strategies.
  • 3.1K
  • 28 Apr 2022
Topic Review
Taiaha
A taiaha (Māori pronunciation: [ˈtaiaha]) is a traditional weapon of the Māori of New Zealand; a close-quarters staff weapon made from either wood or whalebone, and used for short, sharp strikes or stabbing thrusts with efficient footwork on the part of the wielder. Taiaha are usually between 5 to 6 feet (1.5 to 1.8 m) in length. It has three main parts; the arero (tongue), used for stabbing the opponent and parrying; the upoko (head), the base from which the tongue protrudes; and the ate (liver) or tinana (body), the long flat blade which is also used for striking and parrying.
  • 3.1K
  • 08 Nov 2022
Topic Review
Biological Activities of Chlorogenic Acids
The chlorogenic acids (CGAs) are a class of phenolic compounds widely distributed in various plants sources such as fruits, vegetables, coffee beans, tea, apples, and wine. CGAs are esters of quinic acid (QA) and one trans-cinnamic acid residue such as caffeic acid (CA), p-coumaric acid (p-CoA), and ferulic acid (FA), which are known as caffeoylquinic acids (CQAs), p-coumaroylquinic acids (p-CoQAs) and feruloylquinic acid (FQAs).
  • 3.1K
  • 10 Jun 2022
Topic Review
Measuring Biosignals with Single Circuit Boards
To measure biosignals constantly, using textile-integrated or even textile-based electrodes and miniaturized electronics, is ideal to provide maximum comfort for patients or athletes during monitoring. While in former times, this was usually solved by integrating specialized electronics into garments, either connected to a handheld computer or including a wireless data transfer option, nowadays increasingly smaller single circuit boards are available, e.g., single-board computers such as Raspberry Pi or microcontrollers such as Arduino, in various shapes and dimensions.
  • 3.1K
  • 01 Mar 2022
Topic Review
Microalgae Cultivation Techniques and Growth Conditions
Microalgae, constituting a wide range of photosynthetic organisms, span from fundamental blue-green algae (cyanobacteria/prokaryotes) to complex seaweeds, rendering them one of the most diverse groups in the biological kingdom.
  • 3.1K
  • 12 Mar 2024
Topic Review
Relaxor Ferroelectrics for Energy Storage
Ferroelectrics (FE) are polar materials with spontaneous polarization that can be reoriented by changing the direction of the external applied electric field.
  • 3.1K
  • 08 Feb 2021
Topic Review
Autonomous Underwater Vehicles
Development of Autonomous Underwater Vehicles (AUV's) has permitted the automatization of many tasks originally achieved with manned vehicles in underwater environments. Teams of AUV's designed to work within a common mission are opening the possibilities for new and more complex applications. In underwater environments, communication, localization, and navigation of AUV's are considered challenges due to the impossibility of relying on radio communications and global positioning systems. For a long time, acoustic systems have been the main approach for solving these challenges. However, they present their own shortcomings, which are more relevant for AUV's teams. As a result, researchers have explored different alternatives. To summarize and analyze these alternatives, a review of the literature is presented in this paper. Finally, a summary of collaborative AUV's teams and missions is also included, with the aim of analyzing their applicability, advantages, and limitations.
  • 3.1K
  • 28 Oct 2020
Topic Review
Anti-Icing Surfaces
In numerous fields such as aerospace, the environment, and energy supply, ice generation and accretion represent a severe issue. For this reason, numerous methods have been developed for ice formation to be delayed and/or to inhibit ice adhesion to the substrates. Among them, laser micro/nanostructuring of surfaces aiming to obtain superhydrophobic behavior has been taken as a starting point for engineering substrates with anti-icing properties. 
  • 3.1K
  • 17 Mar 2021
Topic Review
The Samcheong Hanok
In Bukchon, the most representative hanok village in Seoul, there is a unique hanok, or traditional Korean house, which also looks modern. Originally built around 1940, the house underwent several stages of extension and repairs, and in 2000, was renovated by architect Wook Choi (born 1963) who called it “Samcheong Hanok” (or Samchung Hanok). Arguably, the evolution of the Samcheong Hanok illustrates a typical history of modern hanok in the past century. In the history, sudden increases in the number of hanok buildings were detected around two specific periods: first, approximately in the three decades from the early 1930s; second, in the past two decades from 2000. This phenomenon leads to classification of the hanok as urban-type or contemporary, according to whether they were built in the first or second period, respectively.
  • 3.1K
  • 03 Sep 2021
Topic Review
UAVs in the U.S. Military
As of January 2014, the U.S. military operates a large number of unmanned aerial systems (UAVs or Unmanned Air Vehicles): 7,362 RQ-11 Ravens; 990 AeroVironment Wasp IIIs; 1,137 AeroVironment RQ-20 Pumas; and 306 RQ-16 T-Hawk small UAS systems and 246 Predators and MQ-1C Grey Eagles; 126 MQ-9 Reapers; 491 RQ-7 Shadows; and 33 RQ-4 Global Hawk large systems. The military role of unmanned aircraft systems is growing at unprecedented rates. In 2005, tactical- and theater-level unmanned aircraft alone had flown over 100,000 flight hours in support of Operation Enduring Freedom and Operation Iraqi Freedom, in which they are organized under Task Force Liberty in Afghanistan and Task Force ODIN in Iraq. Rapid advances in technology are enabling more and more capability to be placed on smaller airframes, which is spurring a large increase in the number of Small Unmanned Aircraft Systems (SUAS) being deployed on the battlefield. The use of SUAS in combat is so new that no formal DoD wide reporting procedures have been established to track SUAS flight hours. As the capabilities grow for all types of UAS, nations continue to subsidize their research and development, leading to further advances and enabling them to perform a multitude of missions. UAS no longer only perform intelligence, surveillance, and reconnaissance missions, although this still remains their predominant type. Their roles have expanded to areas including electronic attack, drone strikes, suppression or destruction of enemy air defense, network node or communications relay, combat search and rescue, and derivations of these themes. These UAS range in cost from a few thousand dollars to tens of millions of dollars, with aircraft ranging from less than one pound to over 40,000 pounds.
  • 3.1K
  • 14 Oct 2022
Topic Review
Ring
Ring LLC is a home security and smart home company owned by Amazon. Ring manufactures home security products that incorporate outdoor surveillance cameras, including the Ring Video Doorbell smart doorbell, and hosts an app, Neighbors, for online social sharing of captured footage among users. Ring also provides video footage from its cameras and data from its Neighbors app to law enforcement agencies on request. Its police partnerships have been criticized by civil rights advocacy groups as building an invasive private surveillance network.
  • 3.1K
  • 18 Oct 2022
Topic Review
Carbon-Burning Process
The carbon-burning process or carbon fusion is a set of nuclear fusion reactions that take place in the cores of massive stars (at least 8 [math]\displaystyle{ \begin{smallmatrix}M \odot\end{smallmatrix} }[/math] at birth) that combines carbon into other elements. It requires high temperatures (> 5×108 K or 50 keV) and densities (> 3×109 kg/m3). These figures for temperature and density are only a guide. More massive stars burn their nuclear fuel more quickly, since they have to offset greater gravitational forces to stay in (approximate) hydrostatic equilibrium. That generally means higher temperatures, although lower densities, than for less massive stars. To get the right figures for a particular mass, and a particular stage of evolution, it is necessary to use a numerical stellar model computed with computer algorithms. Such models are continually being refined based on nuclear physics experiments (which measure nuclear reaction rates) and astronomical observations (which include direct observation of mass loss, detection of nuclear products from spectrum observations after convection zones develop from the surface to fusion-burning regions – known as dredge-up events – and so bring nuclear products to the surface, and many other observations relevant to models).
  • 3.1K
  • 17 Nov 2022
Topic Review
Thalassocnus
Thalassocnus is an extinct genus of semiaquatic ground sloths from the Miocene and Pliocene of the Pacific South American coast. It is monotypic within the subfamily Thalassocninae. The five species—T. antiquus, T. natans, T. littoralis, T. carolomartini, and T. yuacensis—represent a chronospecies, a population gradually adapting to marine life in one direct lineage. They are the only known aquatic sloths. They have been found in the Pisco Formation of Peru and the Bahía Inglesa, Coquimbo, and Horcón formations of Chile. Thalassocninae has been placed in both the families Megatheriidae and Nothrotheriidae. Thalassocnus evolved several marine adaptations over the course of 4 million years, such as dense and heavy bones to counteract buoyancy, the internal nostrils migrating farther into the head to help with breathing while completely submerged, the snout becoming wider and more elongated to consume aquatic plants better, and the head angling farther and farther downwards to aid in bottom feeding. The long tail was probably used for diving and balance similarly to the modern day beaver (Castor spp.) and platypus (Ornithorhynchus anatinus). Thalassocnus probably walked across the seafloor and dug up food with its claws. They probably could not do high-powered swimming, relying on paddling if necessary. Early Thalassocnus were probably generalist grazers eating seaweed and seagrasses close to shore, whereas later species specialized on seagrasses farther off the coast. They were probably preyed upon by sharks and macroraptorial sperm whales such as Acrophyseter. Thalassocnus were found in formations with large marine mammal and shark assemblages.
  • 3.1K
  • 27 Sep 2022
Topic Review
Plant Nutrition under Climate Change
The climate is one of the key elements impacting several cycles connected to soil and plant systems, as well as plant production, soil quality, and environmental quality. Due to heightened human activity, the rate of CO2 is rising in the atmosphere. Changing climatic conditions (such as temperature, CO2, and precipitation) influence plant nutrition in a range of ways, comprising mineralization, decomposition, leaching, and losing nutrients in the soil.
  • 3.1K
  • 26 Jan 2022
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