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Topic Review
Glass–Ceramics
Owing to their combinations of unique properties of sintered ceramics and the distinctive characteristics of glasses, glass-ceramics have attracted great interest from both academia and industry worldwide since their accidental discovery in 1953.
  • 5.3K
  • 27 Oct 2020
Topic Review
Role of Chloroplast Gene Expression
 Chloroplasts are plant organelles that carry out photosynthesis, produce various metabolites, and sense changes in the external environment. Given their endosymbiotic origin, chloroplasts have retained independent genomes and gene-expression machinery. Most genes from the prokaryotic ancestors of chloroplasts were transferred into the nucleus over the course of evolution. However, the importance of chloroplast gene expression in environmental stress responses have recently become more apparent. Here, we discuss the emerging roles of the distinct chloroplast gene expression processes in plant responses to environmental stresses. For example, the transcription and translation of psbA play an important role in high-light stress responses. A better understanding of the connection between chloroplast gene expression and environmental stress responses is crucial for breeding stress-tolerant crops better able to cope with the rapidly changing environment. Chloroplasts are plant organelles that carry out photosynthesis, produce various metabolites, and sense changes in the external environment. Given their endosymbiotic origin, chloroplasts have retained independent genomes and gene-expression machinery. Most genes from the prokaryotic ancestors of chloroplasts were transferred into the nucleus over the course of evolution. However, the importance of chloroplast gene expression in environmental stress responses have recently become more apparent.
  • 5.3K
  • 02 Sep 2020
Topic Review
Prime Video
Prime Video, also marketed as Amazon Prime Video, is an American Internet video on demand service that is developed, owned, and operated by Amazon. It offers television shows and films for rent or purchase and Prime Video, a selection of Amazon Studios original content and licensed acquisitions included in the Amazon's Prime subscription. In the United Kingdom , United States , Germany , and many other territories, access to Prime Video is also available through a video-only membership, which does not require a full Prime subscription. In France and Italy, and other countries like Australia , Canada , India , etc. Prime Video content is only accessible through a dedicated Prime Video website. In some countries Prime Video additionally offers Amazon Channels, which allows viewers to subscribe to other suppliers' content, including HBO in the United States. Launched on September 7, 2006 as Amazon Unbox in the United States, the service grew with its expanding library, and added the Prime Video membership with the development of Prime. It was then renamed as Amazon Instant Video on Demand. After acquiring the local streaming and DVD-by-mail service LoveFilm in 2011, Prime Video was added to Prime in the United Kingdom, Germany and Austria in 2014, a move that angered some Prime UK members as the bundling was non-negotiable with a 61% increase in subscription fee. In the UK, Germany, and Austria, Prime Video has been available on a monthly subscription of £5.99 or €7.99 per month, continuing the plan of LoveFilm Instant. The service was previously available in Norway , Denmark and Sweden in 2012, but was discontinued in 2013. On April 18, 2016, Amazon split Prime Video from Amazon Prime in the US for $8.99 per month. The service also hosts Amazon Original content alongside titles on Video as well. On December 14, 2016, Prime Video launched worldwide (except for Mainland China, Cuba, Iran, North Korea, Syria) expanding its reach beyond the US, the UK, Germany, Austria, and Japan. Among the new territories, the service was included with Prime in Belgium, Canada , France , India , Italy, Spain , Poland , and Brazil , while for all other countries – for instance Bulgaria – it was made available for a monthly promotional price of $/€2.99 per month for the first six months and $/€5.99 per month thereafter.
  • 5.3K
  • 29 Nov 2022
Topic Review
Courtship
Courtship is the period of development towards an intimate relationship wherein a couple get to know each other and decide if there will be an engagement, followed by a marriage. A courtship may be an informal and private matter between two people or may be a public affair, or a formal arrangement with family approval. Traditionally, in the case of a formal engagement, it is the role of a male to actively "court" or "woo" a female, thus encouraging her to understand him and her receptiveness to a marriage proposal.
  • 5.3K
  • 25 Nov 2022
Topic Review
Olefins Production via Steam Cracking:Effect of Operating Parameters
Various parameters need to be considered to optimize a pyrolysis reactor for the production of ethylene and propylene. These parameters are included temperature, residence time, steam-to-hydrocarbon ratio, and feedstock composition. A higher reaction temperature results in a higher yield of ethylene, a shorter residence time, and higher reaction velocities. A low operating pressure is preferred for this process because of the gas phase reaction inside the reactor tubes and the production of more gaseous molecules for its reactions to the right. The reactor pressure must be kept as low as possible (between 170 and 250 kPa). The gas pressure in the reactor tube outlet is indirectly adjusted by the suction process gas pressure of the compressor in the compression section, downstream of the process. As mentioned earlier, to reach lower hydrocarbon pressures, process steam is co-fed with the hydrocarbon feed to reduce the hydrocarbon partial pressure and lower coke deposition. The addition of steam decreases the partial pressure of the hydrocarbon feed and favors the formation of primary products.
  • 5.3K
  • 16 Dec 2021
Topic Review
Natural Hazards in Pakistan
Natural hazards are dynamic and unpredictable events that are a continuous threat to global socio-economic development. Humans’ reactions to these catastrophes are influenced by their proximity to the hazards and their ability to anticipate, resist, cope with, and recover from their consequences. Due to climatic changes, the risk of multiple natural hazards is expected to increase in several regions of Pakistan.
  • 5.3K
  • 08 Feb 2023
Topic Review
African Humid Period
The African humid period (AHP) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses, trees and lakes was caused by changes in Earth's orbit around the Sun; changes in vegetation and dust in the Sahara which strengthened the African monsoon; and increased greenhouse gases, which may, or may not imply that anthropogenic global warming could result in a shrinkage of the Sahara desert. During the preceding last glacial maximum, the Sahara contained extensive dune fields and was mostly uninhabited. It was much larger than today, but its lakes and rivers such as Lake Victoria and the White Nile were either dry or at low levels. The humid period began about 14,600–14,500 years ago at the end of Heinrich event 1, simultaneously to the Bølling-Allerød warming. Rivers and lakes such as Lake Chad formed or expanded, glaciers grew on Mount Kilimanjaro and the Sahara retreated. Two major dry fluctuations occurred; during the Younger Dryas and the short 8.2 kiloyear event. The African humid period ended 6,000–5,000 years ago during the Piora Oscillation cold period. While some evidence points to an end 5,500 years ago, in the Sahel, Arabia and East Africa the period appears to have taken place in several steps such as the 4.2 kiloyear event. The AHP led to a widespread settlement of the Sahara and the Arabian Deserts, and had a profound effect on African cultures, such as the birth of the Pharaonic civilization. They lived as hunter-gatherers until the agricultural revolution and domesticated cattle, goats and sheep. They left archeological sites and artifacts such as one of the oldest ships in the world, and rock paintings such as those in the Cave of Swimmers and in the Acacus Mountains. Earlier humid periods in Africa were postulated after the discovery of these rock paintings in now-inhospitable parts of the Sahara. When the period ended, humans gradually abandoned the desert in favour of regions with more secure water supplies, such as the Nile Valley and Mesopotamia, where they gave rise to early complex societies.
  • 5.3K
  • 10 Nov 2022
Topic Review
Factors Influencing Voting Decision
The voting decisions of a population are vital in forming the political structure of a country. Recognizing what influences voters’ selections is key for politicians, candidates, and those crafting policy. 
  • 5.3K
  • 11 Sep 2023
Topic Review
Gaulish Language
Gaulish was an ancient Celtic language that was spoken in parts of Continental Europe before and during the period of the Roman Empire. In the narrow sense, Gaulish was the language spoken by the Celtic inhabitants of Gaul (modern-day France, Luxembourg, Belgium, most of Switzerland, Northern Italy, as well as the parts of the Netherlands and Germany on the west bank of the Rhine). In a wider sense, it also comprises varieties of Celtic that were spoken across much of central Europe ("Noric"), parts of the Balkans, and Anatolia ("Galatian"), which are thought to have been closely related. The more divergent Lepontic of Northern Italy has also sometimes been subsumed under Gaulish. Together with Lepontic and the Celtiberian language spoken in the Iberian Peninsula, Gaulish helps form the geographic group of Continental Celtic languages. The precise linguistic relationships among them, as well as between them and the modern Insular Celtic languages, are uncertain and a matter of ongoing debate because of their sparse attestation. Gaulish is found in some 800 (often fragmentary) inscriptions including calendars, pottery accounts, funeral monuments, short dedications to gods, coin inscriptions, statements of ownership, and other texts, possibly curse tablets. Gaulish texts were first written in the Greek alphabet in southern France and in a variety of the Old Italic script in northern Italy. After the Roman conquest of those regions, writing shifted to the use of the Latin alphabet. During his conquest of Gaul, Caesar reported that the Helvetii were in possession of documents in the Greek script, and all Gaulish coins used the Greek script until about 50 BC. Gaulish in Western Europe was supplanted by Vulgar Latin and various Germanic languages from around the 5th century AD onwards. It is thought to have gone extinct some time around the late 6th century.
  • 5.3K
  • 01 Dec 2022
Topic Review
DNA Excision Repairs and Implication
The physiological impact of the aberrant oxidation products on genomic DNA were demonstrated by embryonic lethality or the cancer susceptibility and/or neurological symptoms of  animal impaired in the base excision repair (BER); the major pathway to maintain genomic integrity against non-bulky DNA oxidation. However, growing evidence suggests that other DNA repair pathways or factors that are not primarily associated with the classical BER pathway are also actively involved in the mitigation of oxidative assaults on the genomic DNA, according to the corresponding types of DNA oxidation. Among others, factors dedicated to lesion recognition in the nucleotide excision repair (NER) pathway have been shown to play eminent roles in the process of lesion recognition and stimulation of the enzyme activity of some sets of BER factors. Besides, substantial bulky DNA oxidation can be preferentially removed by a canonical NER mechanism; therefore, loss of function in the NER pathway shares common features arising from BER defects, including cancer predisposition and neurological disorders, although NER defects generally are nonlethal.
  • 5.3K
  • 30 Oct 2020
Topic Review
Synthetic Aperture Radar
SAR constellations 
  • 5.3K
  • 24 Aug 2020
Biography
Jean Piaget
Jean Piaget (UK: /piˈæʒeɪ/, US: /ˌpiːəˈʒeɪ/;[1] French: [ʒɑ̃ pjaʒɛ]; 9 August 1896 – 16 September 1980) was a Switzerland psychologist known for his work on child development. Piaget's theory of cognitive development and epistemological view are together called "genetic epistemology". Piaget placed great importance on the education of children. As the Director of the Internati
  • 5.3K
  • 21 Nov 2022
Topic Review
Synesthesia
Synesthesia (American English) or synaesthesia (British English) is a perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathway. People who report a lifelong history of such experiences are known as synesthetes. Awareness of synesthetic perceptions varies from person to person. In one common form of synesthesia, known as grapheme–color synesthesia or color–graphemic synesthesia, letters or numbers are perceived as inherently colored. In spatial-sequence, or number form synesthesia, numbers, months of the year, or days of the week elicit precise locations in space (e.g., 1980 may be "farther away" than 1990), or may appear as a three-dimensional map (clockwise or counterclockwise). Synesthetic associations can occur in any combination and any number of senses or cognitive pathways. Little is known about how synesthesia develops. It has been suggested that synesthesia develops during childhood when children are intensively engaged with abstract concepts for the first time. This hypothesis – referred to as semantic vacuum hypothesis – could explain why the most common forms of synesthesia are grapheme–color, spatial sequence, and number form. These are usually the first abstract concepts that educational systems require children to learn. Difficulties have been recognized in adequately defining synesthesia. Many different phenomena have been included in the term synesthesia, and in many cases the terminology seems to be inaccurate. A more accurate but less common term may be ideasthesia. The earliest recorded case of synesthesia is attributed to the Oxford University academic and philosopher John Locke, who, in 1690, made a report about a blind man who said he experienced the color scarlet when he heard the sound of a trumpet. However, there is disagreement as to whether Locke described an actual instance of synesthesia or was using a metaphor. The first medical account came from German physician Georg Tobias Ludwig Sachs in 1812. The term is from the Ancient Greek σύν syn, 'together', and αἴσθησις aisthēsis, 'sensation'.
  • 5.3K
  • 15 Nov 2022
Topic Review
Cat Café
A cat café is a theme café whose attraction is cats who can be watched and played with. Patrons pay a cover fee, generally hourly, and thus cat cafés can be seen as a form of supervised indoor pet rental. "Cat café" has been officially recognized in the online edition of the Oxford Dictionary of English since August 2015.
  • 5.3K
  • 20 Oct 2022
Topic Review
Polish Pension System
Polish’s Pension System was reformed in 1999. The new system is built from three parts. It comprises a public pension and an earnings-related system with notional accounts.  There are also voluntary employer sponsored pension plans.
  • 5.3K
  • 02 Nov 2020
Topic Review
Lithium-Ion Battery Fire Suppression
Lithium-ion Batteries (LiBs) hazards, techniques for mitigating risks, the suppression of LiB fires and identification of shortcomings for future improvement were thoroughly reviewed. Water is identified as an efficient cooling and suppressing agent and water mist is considered the most promising technique to extinguish LiBs fire. 
  • 5.3K
  • 29 Apr 2021
Topic Review
Bonded Marine Hoses for Floating Offshore Structures (FOS)
By characterisation, a marine hose is a unique type of flexible riser used in fluid transfer. By definition, a marine hose is simply a fluid transfer conduit utilised in transferring, discharging, loading, and transporting fluids from an oil well to the platform of a floating platform or a floating structure. The fluid transfer system for bonded marine hoses is dependent on floating offshore structures (FOS). Single Point Mooring (SPM) systems are component aspects of the techno-economic design and FOS operation.
  • 5.3K
  • 28 Mar 2022
Topic Review
Pet Husbandry
Pet husbandry is the practices applied in day-to-day care of animal companions, which can greatly impact animal welfare. Pet husbandry include: (1) origin of pets; (2) number and type of pets in the household; (3) diet type and feeding practices; (4) living environment and daily activities; (5) preventive treatment for parasites and vaccination; (6) regular veterinary check-ups and access to health care; and (7) compliance with legal requirements and identification.
  • 5.3K
  • 29 Oct 2020
Topic Review
Two-Dimensional Space
Two-dimensional space (also known as 2D space, 2-space, or bi-dimensional space) is a geometric setting in which two values (called parameters) are required to determine the position of an element (i.e., point). The set [math]\displaystyle{ \mathbb{R}^2 }[/math] of pairs of real numbers with appropriate structure often serves as the canonical example of a two-dimensional Euclidean space. For a generalization of the concept, see dimension. Two-dimensional space can be seen as a projection of the physical universe onto a plane. Usually, it is thought of as a Euclidean space and the two dimensions are called length and width.
  • 5.3K
  • 28 Nov 2022
Topic Review
Brassicaceae Family
Brassicaceae family vegetables have an ample worldwide distribution, which can be found in all continents except Antarctica. One of the most striking features of this botanical family is the presence of several kinds of secondary metabolites with a distinctive taste, and also interesting bioactivities. The most deeply studied are the glucosinolates (GSL) and from their bioactive breakdown products, the isothiocyanates and the indoles. Moreover, these species are also rich and possess unique profiles of phenolic compounds, carotenoids, and other groups of less studied compounds such as phytoalexins, terpenes, phytosteroids, and tocopherols, here reviewed.
  • 5.3K
  • 29 Oct 2020
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