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Selenography
Selenography is the study of the surface and physical features of the Moon. Historically, the principal concern of selenographists was the mapping and naming of the lunar maria, craters, mountain ranges, and other various features. This task was largely finished when high resolution images of the near and far sides of the Moon were obtained by orbiting spacecraft during the early space era. Nevertheless, some regions of the Moon remain poorly imaged (especially near the poles) and the exact locations of many features (like crater depths) are uncertain by several kilometers. Today, selenography is considered to be a subdiscipline of selenology, which itself is most often referred to as simply "lunar science." The word selenography is derived from the Greek lunar deity Σελήνη Selene and γράφω graphō, "I write".
  • 1.2K
  • 11 Nov 2022
Topic Review
Sediment Quality Triad (SQT)
In aquatic toxicology, the sediment quality triad (SQT) approach has been used as an assessment tool to evaluate the extent of sediment degradation resulting from contaminants released due to human activity present in aquatic environments (Chapman, 1990). This evaluation focuses on three main components: 1.) sediment chemistry, 2.) sediment toxicity tests using aquatic organisms, and 3.) the field effects on the benthic organisms (Chapman, 1990). Often used in risk assessment, the combination of three lines of evidence can lead to a comprehensive understanding of the possible effects to the aquatic community (Chapman, 1997). Although the SQT approach does not provide a cause-and-effect relationship linking concentrations of individual chemicals to adverse biological effects, it does provide an assessment of sediment quality commonly used to explain sediment characteristics quantitatively. The information provided by each portion of the SQT is unique and complementary, and the combination of these portions is necessary because no single characteristic provides comprehensive information regarding a specific site (Chapman, 1997)
  • 346
  • 29 Nov 2022
Topic Review
Second Grinnell Expedition
The Second Grinnell Expedition of 1853 was an American effort, financed by Henry Grinnell, to determine the fate of the Franklin's lost expedition. Led by Dr. Elisha Kane, the team explored areas northwest of Greenland, now called Grinnell Land. While failing to determine the fate of Sir John Franklin, the expedition set a new record for northward penetration, delineated 960 mi (1,540 km) of unexplored coastline north of 82° latitude, and discovered the long-sought open Polar Sea. Kane collected valuable geographical, climate and magnetic observations before abandoning the brig Advance to the pack ice in 1855. While three members of the crew were lost, the epic journey of the survivors inspired the public as a vivid tale of Arctic survival.
  • 237
  • 28 Oct 2022
Topic Review
Second Bulgarian Empire
The Second Bulgarian Empire (Bulgarian: Второ българско царство, Vtorо Bălgarskо Tsarstvo) was a medieval Bulgarian state that existed between 1185 and 1396. A successor to the First Bulgarian Empire, it reached the peak of its power under Tsars Kaloyan and Ivan Asen II before gradually being conquered by the Ottomans in the late 14th and early 15th centuries. It was succeeded by the Principality and later Kingdom of Bulgaria in 1878. Until 1256, the Second Bulgarian Empire was the dominant power in the Balkans, defeating the Byzantine Empire in several major battles. In 1205 Emperor Kaloyan defeated the newly established Latin Empire in the Battle of Adrianople. His nephew Ivan Asen II defeated the Despotate of Epiros and made Bulgaria a regional power again. During his reign, Bulgaria spread from the Adriatic to the Black Sea and the economy flourished. In the late 13th century, however, the Empire declined under constant invasions by Mongols, Byzantines, Hungarians, and Serbs, as well as internal unrest and revolts. The 14th century saw a temporary recovery and stability, but also the peak of Balkan feudalism as central authorities gradually lost power in many regions. Bulgaria was divided into three parts on the eve of the Ottoman invasion. Despite strong Byzantine influence, Bulgarian artists and architects created their own distinctive style. In the 14th century, during the period known as the Second Golden Age of Bulgarian culture, literature, art and architecture flourished. The capital city Tarnovo, which was considered a "New Constantinople", became the country's main cultural hub and the centre of the Eastern Orthodox world for contemporary Bulgarians. After the Ottoman conquest, many Bulgarian clerics and scholars emigrated to Serbia, Wallachia, Moldavia, and Russian principalities, where they introduced Bulgarian culture, books, and hesychastic ideas.
  • 2.4K
  • 10 Oct 2022
Topic Review
Scottish Highlands
The Highlands (Scots: the Hielands; Scottish Gaelic: a’ Ghàidhealtachd [ə ˈɣɛːəl̪ˠt̪ʰəxk], 'the place of the Gaels') is a historical region of Scotland. Culturally, the Highlands and the Lowlands diverged from the Late Middle Ages into the modern period, when Lowland Scots replaced Scottish Gaelic throughout most of the Lowlands. The term is also used for the area north and west of the Highland Boundary Fault, although the exact boundaries are not clearly defined, particularly to the east. The Great Glen divides the Grampian Mountains to the southeast from the Northwest Highlands. The Scottish Gaelic name of A' Ghàidhealtachd literally means "the place of the Gaels" and traditionally, from a Gaelic-speaking point of view, includes both the Western Isles and the Highlands.The area is very sparsely populated, with many mountain ranges dominating the region, and includes the highest mountain in the British Isles, Ben Nevis. During the 18th and early 19th centuries the population of the Highlands rose to around 300,000, but from c. 1841 and for the next 160 years, the natural increase in population was exceeded by emigration (mostly to Canada, the United States, Australia and New Zealand, and migration to the industrial cities of Scotland and England.):xxiii, 414 and passim The area is now one of the most sparsely populated in Europe. At 9.1/km2 (24/sq mi) in 2012, the population density in the Highlands and Islands is less than one seventh of Scotland's as a whole, comparable with that of Bolivia, Chad and Russia . The Highland Council is the administrative body for much of the Highlands, with its administrative centre at Inverness. However, the Highlands also includes parts of the council areas of Aberdeenshire, Angus, Argyll and Bute, Moray, North Ayrshire, Perth and Kinross, Stirling and West Dunbartonshire. The Scottish Highlands is the only area in the British Isles to have the taiga biome as it features concentrated populations of Scots pine forest: see Caledonian Forest. It is the most mountainous part of the United Kingdom .
  • 2.7K
  • 30 Nov 2022
Topic Review
Science, Technology, Society and Environment Education
Science, technology, society and environment (STSE) education, originates from the science technology and society (STS) movement in science education. This is an outlook on science education that emphasizes the teaching of scientific and technological developments in their cultural, economic, social and political contexts. In this view of science education, students are encouraged to engage in issues pertaining to the impact of science on everyday life and make responsible decisions about how to address such issues (Solomon, 1993 and Aikenhead, 1994)
  • 3.5K
  • 20 Oct 2022
Topic Review
Saros
The saros (/ˈsɛərɒs/ (listen)) is a period of exactly 223 synodic months, approximately 6585.3211 days, or 18 years, 10, 11, or 12 days (depending on the number of leap years), and 8 hours, that can be used to predict eclipses of the Sun and Moon. One saros period after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, a near straight line, and a nearly identical eclipse will occur, in what is referred to as an eclipse cycle. A sar is one half of a saros. A series of eclipses that are separated by one saros is called a saros series. It corresponds to: The 19 eclipse years means that if there is a solar eclipse (or lunar eclipse), then after one saros a new moon will take place at the same node of the orbit of the Moon, and under these circumstances another eclipse can occur.
  • 677
  • 22 Nov 2022
Topic Review
Santa Cruz Province, Argentina
Santa Cruz Province (Spanish: Provincia de Santa Cruz, Spanish pronunciation: [ˈsanta ˈkɾus], 'Holy Cross') is a province of Argentina , located in the southern part of the country, in Patagonia. It borders Chubut Province to the north, and Chile to the west and south, with an Atlantic coast on its east. Santa Cruz is the second-largest province of the country (after Buenos Aires Province), and the least densely populated in mainland Argentina. The indigenous people of the province are the Tehuelches, who despite European exploration from the 16th century onwards, retained independence until the late 19th century. Soon after the Conquest of the Desert in the 1870s, the area was organised as the Territory of Santa Cruz, named after its original capital in Puerto Santa Cruz. The capital moved to Rio Gallegos in 1888 and has remained there ever since. Immigrants from various European countries came to the territory in the late 19th and early 20th century during a gold rush. Santa Cruz became a province of Argentina in 1957.
  • 734
  • 30 Oct 2022
Topic Review
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Quartz-bearing sandstone can be converted into quartzite through metamorphism, usually related to tectonic compression within orogenic belts.
  • 4.4K
  • 15 Nov 2022
Topic Review
Role of ACE2 in Gut
A vital factor of viral pathogenesis involves the angiotensin-converting enzyme-2 (ACE2) cellular receptor, which facilitates entry of the virus into susceptible cells. The receptor-binding domain of the spike protein binds to the ACE2 receptor activating membrane fusion of the virus to the host cell. Subsequently, viral RNA is released into the cytoplasm, and the infection is established. The gut microbiota is shaped by our diet; therefore, a healthy gut is important for optimal metabolism, immunology and protection of the host. 
  • 575
  • 21 Mar 2022
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