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.]

Cosmology revisited

So first of all, I know a handful readers or two came by after I commented over at William’s blog – if one or more of you decided to come back to read this: Welcome!

If you didn’t read this post (that is: looked closely at the images) back when I posted that, I suggest you start there. Now Salman Khan has made a series of videos where he starts at Earth, then moves on outwards. I notice in one of the videos he mistakenly uses light year as a measure of time, not distance, but he was pretty excited at that point, for good reason. I’ve posted the first video in the series below – when I watched it on youtube, it automatically started the next video once the previous one had finished, which was both good and bad as I probably sat there for over an hour watching that stuff, but I don’t know if it’ll do the same when embedded here. If not, you should really watch the series on youtube if you think the first part was ok – it gets even better and far more mind boggling as he proceeds.

I love what Sal is doing. If you felt the need to follow the link to Salman Khan’s wikipedia article because you don’t know who he is or what he’s doing, here’s another good video you should watch:

And here’s the link to the site.

…

In other news, here’s a chess game I played earlier this evening (I was white and it was a 5 minute game so presumably lots of mistakes if you let the silicon monster have a look at it). I haven’t run it through a computer, but I still think my decision to exchange on g7 and move 20.f5 instead of taking on e6 was the right one. I really liked that 20.f5 move when I played it. If black wants to survive, he can’t defend that e6 pawn anyway, i.e. 20…Nf8, 21.f6+ Kg8, 22.Qd2 Nbd7, 23.Qh6 Nf6 (…Ne6, 24.dxe6 Nxf6(□), 25.Nxf6+ Qxf6(□), 26.Rxf6 and white has the same win as in the game with the Nf3 and Ng5-manoeuvre), 24.Nxf6+ Kg8, 25.Nh5! Ne6 (…gxh5 and after 26.Rxf7 black is mated), 26.dxe6 Rg8(□), 27.exf7 and game over). I think 20.f6 was a better defence than Ne5, Ne5 was a bad move. Black needs all the support he can get of the black squares around his king after he’s allowed the exchange of the g7-bishop. That said, the position after f6 is still losing for black.