Econstudentlog

Wikipedia articles of interest

Because of computer problems I have not spent much time on wikipedia lately, so quite a few of these are related to the book I’m reading at the moment – but I lost a post to stupidity (what I had written was not publishable, nor could it be turned into something that was) and I thought I should at least post something, as I’m leaving town tomorrow (it’s my birthday in a few days’ time) and don’t know at this point if I’ll have time and opportunity to post anything for the next few days.

i. Insect morphology.

Some of the images in that article (‘examples of mandibles’) would probably have given me nightmares if I’d been shown them at an early age. It’s a pretty neat article.

ii. Uniformitarianism.

“Uniformitarianism is the assumption that the same natural laws and processes that operate in the universe now, have always operated in the universe in the past and apply everywhere in the universe. It has included the gradualistic concept that “the present is the key to the past” and is functioning at the same rates. Uniformitarianism has been a key principle of geology and virtually all fields of science, but naturalism’s modern geologists, while accepting that geology has occurred across deep time, no longer hold to a strict gradualism.”

iii. Oceanic trench.

“The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor.

Trenches are found at the boundary between two lithospheric plates. There are three types of lithospheric plate boundaries: divergent (where lithosphere and oceanic crust is created at mid-ocean ridges), convergent (where one lithospheric plate sinks beneath another and returns to the mantle), and transform (where two lithospheric plates slide past each other).”

iv. White stork (featured).

“The White Stork (Ciconia ciconia) is a large bird in the stork family Ciconiidae. Its plumage is mainly white, with black on its wings. Adults have long red legs and long pointed red beaks, and measure on average 100–115 cm (39–45 in) from beak tip to end of tail, with a 155–215 cm (61–85 in) wingspan. The two subspecies, which differ slightly in size, breed in Europe (north to Finland), northwestern Africa, southwestern Asia (east to southern Kazakhstan), and southern Africa. The White Stork is a long-distance migrant, wintering in Africa from tropical Sub-Saharan Africa to as far south as South Africa, or on the Indian subcontinent. When migrating between Europe and Africa, it avoids crossing the Mediterranean Sea and detours via the Levant in the east or the Strait of Gibraltar in the west, because the air thermals on which it depends do not form over water.

A carnivore, the White Stork eats a wide range of animal prey, including insects, fish, amphibians, reptiles, small mammals, and small birds. It takes most of its food from the ground, among low vegetation, and from shallow water. It is a monogamous breeder, but does not pair for life. Both members of the pair build a large stick nest, which may be used for several years. Each year the female can lay one clutch of usually four eggs, which hatch asynchronously 33–34 days after being laid. Both parents take turns incubating the eggs and both feed the young. The young leave the nest 58–64 days after hatching, and continue to be fed by the parents for a further 7–20 days.”

v. Weathering.

“Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth’s atmosphere, biota and waters. Weathering occurs in situ, or “with no movement”, and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, snow, wind and gravity.

Two important classifications of weathering processes exist – physical and chemical weathering. Mechanical or physical weathering involves the breakdown of rocks and soils through direct contact with atmospheric conditions, such as heat, water, ice and pressure. The second classification, chemical weathering, involves the direct effect of atmospheric chemicals or biologically produced chemicals (also known as biological weathering) in the breakdown of rocks, soils and minerals.[1]

The materials left over after the rock breaks down combined with organic material creates soil. The mineral content of the soil is determined by the parent material, thus a soil derived from a single rock type can often be deficient in one or more minerals for good fertility, while a soil weathered from a mix of rock types (as in glacial, aeolian or alluvial sediments) often makes more fertile soil. In addition many of Earth’s landforms and landscapes are the result of weathering processes combined with erosion and re-deposition.”

vi. Soil.

Soil is a natural body that consists of layers (soil horizons), composed primarily of minerals that differ from their parent materials in their texture, structure, consistency, color, chemical, biological and other physical characteristics.[1] The result, soil, is the end product of the influence of the climate (temperature, precipitation), relief (slope), organisms (flora and fauna), parent materials (original minerals), temperature, and time. In engineering, soil is referred to as regolith, or loose rock material. Strictly speaking, soil is the depth of regolith that influences and has been influenced by plant roots and may range in depth from centimeters to many meters.

Soil is composed of particles of broken rock (parent materials) that have been altered by chemical and mechanical processes that include weathering (disintegration) with associated erosion (movement). Soil is altered from its parent material by the interactions between the lithosphere, hydrosphere, atmosphere, and biosphere.[2] It is a mixture of mineral and organic materials that are in the form of solids, gasses and liquids.[3][4] Soil is commonly referred to as “earth” or “dirt“; technically, the term “dirt” should be restricted to displaced soil.[5]

Soil forms a structure filled with pore spaces and can be thought of as a mixture of solids, water, and air (gas).[6] Accordingly, soils are often treated as a three-state system.[7] Most soils have a density between 1 and 2 g/cm³.[8] Little of the soil of planet Earth is older than the Tertiary and none is older than the Pleistocene.[9]” (the article has a lot more)

vii. Troxler’s fading

Troxler’s fading or Troxler’s effect is a phenomenon of visual perception. When one fixates a particular point, after about 20 seconds or so, a stimulus away from the fixation point, in peripheral vision, will fade away and disappear. The effect is enhanced if the stimulus is small, is of low contrast or equiluminant, or is blurred. The effect is enhanced the further the stimulus is away from the fixation point.” (there’s a neat example in the article which you shouldn’t miss).

viii. Kuiper belt (featured).

July 30, 2012 - Posted by | astronomy, biology, Geology, wikipedia

4 Comments »

  1. Off topic: Jeg kan huske, du godt kan lide Less Wrong. Har du set, der bliver arrangeret meetups i København? Fx nu på søndag: http://lesswrong.com/meetups/c9 / https://groups.google.com/forum/?fromgroups#!forum/less-wrong-copenhagen

    Comment by Lasse Birk Olesen | July 31, 2012 | Reply

    • Jeg skal nok kikke forbi da jeg alligevel er i KBH i forbindelse med en demonstration (for narkotikalovgivningsreform).

      Comment by Emil | August 1, 2012 | Reply

  2. Jeg tænker, at det kan være mennesker, som du vil føle, du har mere til fælles med, end dem man møder i de fleste andre sammenhænge.

    Comment by Lasse Birk Olesen | July 31, 2012 | Reply

    • Bare så du ved det: Jeg læser ikke lesswrong regelmæssigt længere; kvaliteten har efter min opfattelse været dalende i lang tid.

      Når det er sagt var jeg opmærksom på, at lw arrangerer møder i København – og nej, jeg har ingen planer om at være i København på søndag. Jeg er ikke helt sikker på, at jeg ville deltage i et lw-møde arrangeret i Århus. Jeg er sikker på, at jeg ikke vil rejse langt for at deltage i den slags.

      Et lw-møde i Århus er i øvrigt næppe på trapperne; en af de væsentligste motivationsfaktorer for deltagere ved et sådant møde ville være etableringen af social kontakt med andre som er bekendte med sitet. Den kontakt er allerede for i al fald tre af (/eks)læsernes vedkommende etableret på anden vis.

      Comment by US | August 1, 2012 | Reply


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