Greenland ice sheetThe Greenland ice sheet (Grønlands indlandsis, Sermersuaq) is a vast body of ice covering , roughly near 80% of the surface of Greenland. It is sometimes referred to as an ice cap, or under the term inland ice, or its Danish equivalent, indlandsis. The acronym GIS is frequently used in the scientific literature. It is the second largest ice body in the world, after the Antarctic ice sheet. The ice sheet is almost long in a north–south direction, and its greatest width is at a latitude of 77°N, near its northern margin.
IsotopologueIn chemistry, isotopologues are molecules that differ only in their isotopic composition. They have the same chemical formula and bonding arrangement of atoms, but at least one atom has a different number of neutrons than the parent. An example is water, whose hydrogen-related isotopologues are: "light water" (HOH or ), "semi-heavy water" with the deuterium isotope in equal proportion to protium (HDO or ), "heavy water" with two deuterium isotopes of hydrogen per molecule ( or ), and "super-heavy water" or tritiated water ( or , as well as and , where some or all of the hydrogen atoms are replaced with the radioactive tritium isotope).
Fish scaleA fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as well as possible hydrodynamic advantages. The term scale derives from the Old French escale, meaning a shell pod or husk. Scales vary enormously in size, shape, structure, and extent, ranging from strong and rigid armour plates in fishes such as shrimpfishes and boxfishes, to microscopic or absent in fishes such as eels and anglerfishes.
Fall of the Western Roman EmpireThe fall of the Western Roman Empire, also called the fall of the Roman Empire or the fall of Rome, was the loss of central political control in the Western Roman Empire, a process in which the Empire failed to enforce its rule, and its vast territory was divided into several successor polities. The Roman Empire lost the strengths that had allowed it to exercise effective control over its Western provinces; modern historians posit factors including the effectiveness and numbers of the army, the health and numbers of the Roman population, the strength of the economy, the competence of the emperors, the internal struggles for power, the religious changes of the period, and the efficiency of the civil administration.
Succession of the Roman EmpireThe continuation, succession, and revival of the Roman Empire is a running theme of the history of Europe and the Mediterranean Basin. It reflects the lasting memories of power and prestige associated with the Roman Empire. Several polities have claimed immediate continuity with the Roman Empire, using its name or a variation thereof as their own exclusive or non-exclusive self-description. As centuries went by and more political ruptures occurred, the idea of institutional continuity became increasingly debatable.
Holy Roman EmpireThe Holy Roman Empire, also known as the Holy Roman Empire of the German Nation after 1512, was a political entity usually headed by the Holy Roman Emperor in Central and Western Europe. It developed in the Early Middle Ages and continued until its dissolution in 1806 during the Napoleonic Wars. On 25 December 800, Pope Leo III crowned the Frankish king Charlemagne as Roman emperor, reviving the title in Western Europe more than three centuries after the fall of the ancient's Western Roman Empire in 476.
Medieval philosophyMedieval philosophy is the philosophy that existed through the Middle Ages, the period roughly extending from the fall of the Western Roman Empire in the 5th century until after the Renaissance in the 13th and 14th centuries. Medieval philosophy, understood as a project of independent philosophical inquiry, began in Baghdad, in the middle of the 8th century, and in France, in the itinerant court of Charlemagne, in the last quarter of the 8th century.
Middle AgesIn the history of Europe, the Middle Ages or medieval period (also spelled mediæval or mediaeval) lasted approximately from the late 5th to the late 15th centuries, aligning with the post-classical period of global history. It began with the fall of the Western Roman Empire in 476 AD and ended with the fall of Constantinople in 1453 AD before transitioning into the Renaissance and then the Age of Discovery. The Middle Ages is the middle period of the three traditional divisions of Western history: antiquity, medieval, and modern.
Biogenic substanceA biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of plants or animals. In context of molecular biology, biogenic substances are referred to as biomolecules. They are generally isolated and measured through the use of chromatography and mass spectrometry techniques.
Historiography of the fall of the Western Roman EmpireThe causes and mechanisms of the fall of the Western Roman Empire are a historical theme that was introduced by historian Edward Gibbon in his 1776 book The History of the Decline and Fall of the Roman Empire. Though Gibbon was not the first to speculate on why the empire collapsed, he was the first to give a well-researched and well-referenced account of the event, and started an ongoing historiographical discussion about what caused the fall of the Western Roman Empire.
