Econstudentlog

Wikipedia articles of interest

1. Milankovitch cycles.

“Milankovitch theory describes the collective effects of changes in the Earth’s movements upon its climate, named after Serbian civil engineer and mathematician Milutin Milanković, who worked on it during First World War internment. Milanković mathematically theorized that variations in eccentricity, axial tilt, and precession of the Earth’s orbit determined climatic patterns on Earth through orbital forcing.

The Earth’s axis completes one full cycle of precession approximately every 26,000 years. At the same time the elliptical orbit rotates more slowly. The combined effect of the two precessions leads to a 21,000-year period between the seasons and the orbit. In addition, the angle between Earth’s rotational axis and the normal to the plane of its orbit (obliquity) oscillates between 22.1 and 24.5 degrees on a 41,000-year cycle. It is currently 23.44 degrees and decreasing.”

2. Gravity of Earth. Here’s more, somewhat related.

3. Histone.

4. Lake Victoria.

“With a surface area of 68,800 square kilometres (26,600 sq mi), Lake Victoria is Africa’s largest lake by area, and it is the largest tropical lake in the world. Lake Victoria is the world’s second largest freshwater lake by surface area (only Lake Superior in North America is larger). In terms of its volume, Lake Victoria is the world’s eighth largest continental lake, and it contains about 2,750 cubic kilometers (2.2 billion acre-feet) of water.

[…]

“The introduction of the Nile perch had a decisive impact on Haplochromis stocks which it favoured as its prey, affecting both their abundance and diversity. It is believed that the contribution of this species flock to the fish biomass of the lake has decreased from 80% to less than 1% since the introduction of the Nile perch,[18][33] and that some 65% of the Haplochromis species were driven to extinction in the process, an event which may well represent the largest extinction event amongst vertebrates in the 20th century.[17]

Freed from their evolutionary predators, populations of the diminutive endemic silver cyprinid Rastrineobola argentea (omena in Luo, mukene in Luganda and dagaa in Swahili), flourished, developing into huge shoals. In turn, Pied Kingfisher (Ceryle rudis) populations, that had hitherto fed on haplochromines, exploded in response to this new food source.[34] Similar and other impacts have propagated throughout the ecosystem.

[…]

The Nile perch ‘boom’ was to accelerate and massively expand this process. It coincided with an emerging European market for high-quality white fish meat, prompting the development of industrial fish processing capacity along the lake’s shores in Kisumu, Musoma, Mwanza, Entebbe and Jinja.[40] The export of Nile perch has since expanded away from the European Union (EU) to the Middle East, the United States and Australia, and now represents large foreign exchange earnings to the lake’s riparian states. In Uganda, indeed, its export is second only to coffee in the rankings of export earnings. In 2006, the total value of Nile perch exports from the lake was estimated to be US$ 250 million. […]

With such high demands for Nile perch, the value of the fishery has risen considerably. Labour inflows into the fishery have increased along with growing demand. In 1983, there were an estimated 12,041 boats on the lake. By 2004, there were 51,712, and 153,066 fishermen.[38] The fishery also generates indirect employment for additional multitudes of fish processors, transporters, factory employees and others. All along the lakeshore, ‘boom towns’ have developed in response to the demands of fishing crews with money to spend from a day’s fishing.[Note 4] These towns resemble shanties, and have little in the way of services. Of the 1,433 landing sites identified in the 2004 frame survey, just 20% had communal lavatory facilities, 4% were served by electricity and 6% were served by a potable water supply.[38]”

5. Flesh-fly.

“Flies of the Diptera family Sarcophagidae (from the Greek sarco- = flesh, phage = eating; the same roots as the word “sarcophagus”) are commonly known as flesh flies. Most flesh flies breed in carrion, dung, or decaying material, but a few species lay their eggs in the open wounds of mammals;[1] hence their common name. Some flesh fly larvae are internal parasites of other insects. These larvae, commonly known as maggots, live for about 5–10 days, before descending into the soil and maturing into adulthood. At that stage, they live for 5–7 days. […]

The family contains three subfamilies, the Miltogramminae, the Paramacronychiinae and the Sarcophaginae, containing between them 108 genera. Flesh-flies are quite closely related to the family Calliphoridae, which belongs to the same (large) infraorder, the Muscomorpha, and includes species such as the blowfly that have similar habits to the flesh-flies. [genus/genera is the taxonomic level one step above species. There are a lot of different kinds of flies like this and they are quite successful.]

July 26, 2011 - Posted by | astronomy, biology, cosmology, Geography, Physics, wikipedia

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