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100,000-Year Problem
The 100,000-year problem ("100 ky problem", "100 ka problem") of the Milankovitch theory of orbital forcing refers to a discrepancy between the reconstructed geologic temperature record and the reconstructed amount of incoming solar radiation, or insolation over the past 800,000 years. Due to variations in the Earth's orbit, the amount of insolation varies with periods of around 21,000, 40,000, 100,000, and 400,000 years. Variations in the amount of incident solar energy drive changes in the climate of the Earth, and are recognised as a key factor in the timing of initiation and termination of glaciations. While there is a Milankovitch cycle in the range of 100,000 years, related to Earth's orbital eccentricity, its contribution to variation in insolation is much smaller than those of precession and obliquity. The 100,000-year-problem refers to the lack of an obvious explanation for the periodicity of ice ages at roughly 100,000 years for the past million years, but not before, when the dominant periodicity corresponded to 41,000 years. The unexplained transition between the two periodicity regimes is known as the Mid-Pleistocene Transition, dated to some 800,000 years ago. The related "400,000-year-problem" refers to the absence of a 400,000-year periodicity due to orbital eccentricity in the geological temperature record over the past 1.2 million years. The transition in periodicity from 41,000 years to 100,000 years can now be reproduced in numerical simulations that include a decreasing trend in carbon dioxide and glacially induced removal of regolith, as explained in more detail in the article Mid-Pleistocene Transition.
  • 1.8K
  • 08 Oct 2022
Topic Review
Yukon Wolf
The North American wolf Canis lupus pambasileus is a subspecies of gray wolf that is called the Yukon wolf in Canada and the Alaskan Interior wolf in the United States. It is native to the Alaska Interior and Yukon, save for the tundra region of the Arctic Coast.
  • 2.6K
  • 08 Oct 2022
Topic Review
Idealism in International Relations
Idealism in foreign policy holds that a state should make its internal political philosophy the goal of its foreign policy. For example, an idealist might believe that ending poverty at home should be coupled with tackling poverty abroad. U.S. President Woodrow Wilson was an early advocate of idealism. Wilson's idealism was a precursor to liberal international relations theory, which would arise amongst the "institution-builders" after World War II. It particularly emphasized the ideal of American exceptionalism. More generally, Michael W. Doyle describes idealism as based on the belief that other nations' stated good intentions can be relied on, whereas Realism holds that good intentions are in the long run subject to the security dilemma described by John H. Herz. Hedley Bull wrote: By the 'idealists' we have in mind writers such as Sir Alfred Zimmern, S. H. Bailey, Philip Noel-Baker, and David Mitrany in the United Kingdom, and James T. Shotwell, Pitman Potter, and Parker T. Moon in the United States. ... The distinctive characteristic of these writers was their belief in progress: the belief, in particular, that the system of international relations that had given rise to the First World War was capable of being transformed into a fundamentally more peaceful and just world order; that under the impact of the awakening of democracy, the growth of 'the international mind', the development of the League of Nations, the good works of men of peace or the enlightenment spread by their own teaching, it was in fact being transformed; and that their responsibility as students of international relations was to assist this march of progress to overcome the ignorance, the prejudices, the ill-will, and the sinister interests that stood in its way.
  • 9.2K
  • 09 Oct 2022
Topic Review
MOSE Project
MOSE (MOdulo Sperimentale Elettromeccanico, Experimental Electromechanical Module) is a project intended to protect the city of Venice, Italy, and the Venetian Lagoon from flooding. The project is an integrated system consisting of rows of mobile gates installed at the Lido, Malamocco, and Chioggia inlets that are able to isolate the Venetian Lagoon temporarily from the Adriatic Sea during acqua alta high tides. Together with other measures, such as coastal reinforcement, the raising of quaysides, and the paving and improvement of the lagoon, MOSE is designed to protect Venice and the lagoon from tides of up to 3 metres (9.8 ft). The Consorzio Venezia Nuova is responsible for the work on behalf of the Ministry of Infrastructure and Transport – Venice Water Authority. Construction began simultaneously in 2003. On 10 July 2020, the first full test was successfully completed, and after multiple delays, cost overruns, and scandals resulted in the project missing its 2018 completion deadline (originally a 2011 deadline) it is now expected to be fully completed by the end of 2021.
  • 3.7K
  • 10 Oct 2022
Topic Review
Roadable Aircraft
A roadable aircraft is a type of flying car. It is a hybrid vehicle that combines the flying capability of an aircraft with the option of being driven as an automobile on the ground. The roadable aircraft is typically recognized as a small plane with retractable wings that can fly in the open sky and to drive along roads. Most roadable aircraft have either integrated or modular components. In the U.S., the Defense Advanced Research Projects Agency (DARPA) has shown an interest in the concept with a $65 million program called Transformer to develop a four-person roadable aircraft by 2015. The vehicle is required to take off vertically, and have a 280-mile (450 km) range. AAI Corporation and Lockheed Martin were awarded contracts in late 2010 for the Phase 1 program. Lockheed Martin's design was selected to continue to Phase 3.
  • 3.8K
  • 10 Oct 2022
Topic Review
Phase Resetting in Neurons
Phase resetting in neurons is a behavior observed in different biological oscillators and plays a role in creating neural synchronization as well as different processes within the body. Phase resetting in neurons is when the dynamical behavior of an oscillation is shifted. This occurs when a stimulus perturbs the phase within an oscillatory cycle and a change in period occurs. The periods of these oscillations can vary depending on the biological system, with examples such as: (1) neural responses can change within a millisecond to quickly relay information; (2) In cardiac and respiratory changes that occur throughout the day, could be within seconds; (3) circadian rhythms may vary throughout a series of days; (4) rhythms such as hibernation may have periods that are measured in years. This activity pattern of neurons is a phenomenon seen in various neural circuits throughout the body and is seen in single neuron models and within clusters of neurons. Many of these models utilize phase response (resetting) curves where the oscillation of a neuron is perturbed and the effect the perturbation has on the phase cycle of a neuron is measured.
  • 1.1K
  • 12 Oct 2022
Topic Review
Unix Philosophy
The Unix philosophy, originated by Ken Thompson, is a set of cultural norms and philosophical approaches to minimalist, modular software development. It is based on the experience of leading developers of the Unix operating system. Early Unix developers were important in bringing the concepts of modularity and reusability into software engineering practice, spawning a "software tools" movement. Over time, the leading developers of Unix (and programs that ran on it) established a set of cultural norms for developing software; these norms became as important and influential as the technology of Unix itself; this has been termed the "Unix philosophy." The Unix philosophy emphasizes building simple, short, clear, modular, and extensible code that can be easily maintained and repurposed by developers other than its creators. The Unix philosophy favors composability as opposed to monolithic design.
  • 2.3K
  • 08 Oct 2022
Topic Review
M79 Grenade Launcher
The M79 grenade launcher is a single-shot, shoulder-fired, break-action grenade launcher that fires a 40×46mm grenade, which uses what the US Army calls the High-Low Propulsion System to keep recoil forces low, and first appeared during the Vietnam War. Because of its distinctive report, it has earned the nicknames of "Thumper", "Thump-Gun", "Bloop Tube", "Big Ed", and "Blooper" among American soldiers as well as "Can Cannon" in reference to the grenade size; Australian units referred to it as the "Wombat Gun". The M79 can fire a wide variety of 40 mm rounds, including explosive, anti-personnel, smoke, buckshot, flechette (pointed steel projectiles with a vaned tail for stable flight), and illumination. While largely replaced by the M203, the M79 has remained in service in many units worldwide in niche roles.
  • 7.7K
  • 08 Oct 2022
Topic Review
Core (Game Theory)
In cooperative game theory, the core is the set of feasible allocations that cannot be improved upon by a subset (a coalition) of the economy's agents. A coalition is said to improve upon or block a feasible allocation if the members of that coalition are better off under another feasible allocation that is identical to the first except that every member of the coalition has a different consumption bundle that is part of an aggregate consumption bundle that can be constructed from publicly available technology and the initial endowments of each consumer in the coalition. An allocation is said to have the core property if there is no coalition that can improve upon it. The core is the set of all feasible allocations with the core property.
  • 3.1K
  • 08 Oct 2022
Topic Review
Troppy Effect
Troppy effect – a phenomenon of formation of irregular residual surface wave-like damages resulting from a non-stationary process of cyclic elastoplastic deformation in the zone of contact at rolling friction. It was openly and studied by professor L. A. Sosnovskiy with staff in the framework of Tribo-Fatigue.
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  • 08 Oct 2022
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