Econstudentlog

Wikipedia articles of interest

i. Aedes Albopictus.

“The Tiger mosquito or forest day mosquito, Aedes albopictus (Stegomyia albopicta), from the mosquito (Culicidae) family, is characterized by its black and white striped legs, and small black and white striped body. It is native to the tropical and subtropical areas of Southeast Asia; however, in the past couple of decades this species has invaded many countries throughout the world through the transport of goods and increasing international travel.[1] This mosquito has become a significant pest in many communities because it closely associates with humans (rather than living in wetlands), and typically flies and feeds in the daytime in addition to at dusk and dawn. The insect is called a tiger mosquito because its striped appearance is similar to a tiger. Aedes albopictus is an epidemiologically important vector for the transmission of many viral pathogens, including the West Nile virus, Yellow fever virus, St. Louis encephalitis,[2] dengue fever, and Chikungunya fever,[3] as well as several filarial nematodes such as Dirofilaria immitis. […]

800px-CDC-Gathany-Aedes-albopictus-1
Aedes albopictus
also bites other mammals besides humans and they also bite birds.[19][21] They are always on the search for a host and are both persistent and cautious when it comes to their blood meal and host location. Their blood meal is often broken off short without enough blood ingested for the development of their eggs. This is why Asian tiger mosquitoes bite multiple hosts during their development cycle of the egg, making them particularly efficient at transmitting diseases. The mannerism of biting diverse host species enables the Asian tiger mosquito to be a potential bridge vector for certain pathogens, for example, the West Nile virus that can jump species boundaries. […]

The Asian tiger mosquito originally came from Southeast Asia. In 1966, parts of Asia and the island worlds of India and the Pacific Ocean were denoted as the area of circulation for the Asian tiger mosquito.[30] Since then, it has spread to Europe, the Americas, the Caribbean, Africa and the Middle East. Aedes albopictus is one of the 100 world’s worst invasive species according to the Global Invasive Species Database.[31] […]

In Europe, the Asian tiger mosquito apparently covers an extensive new niche. This means that there are no native, long-established species that conflict with the dispersal of Aedes albopictus. […]

The Asian tiger mosquito was responsible for the Chikungunya epidemic on the French Island La Réunion in 2005–2006. By September 2006, there were an estimated 266,000 people infected with the virus, and 248 fatalities on the island.[54] The Asian tiger mosquito was also the transmitter of the virus in the first and only outbreak of Chikungunya fever on the European continent. […]

Aedes albopictus has proven to be very difficult to suppress or to control due to their remarkable ability to adapt to various environments, their close contact with humans, and their reproductive biology.”

In case you were wondering, the word Aedes comes from the Greek word for “unpleasant”. So, yeah…

ii. Orbital resonance.

“In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. The physics principle behind orbital resonance is similar in concept to pushing a child on a swing, where the orbit and the swing both have a natural frequency, and the other body doing the “pushing” will act in periodic repetition to have a cumulative effect on the motion. Orbital resonances greatly enhance the mutual gravitational influence of the bodies, i.e., their ability to alter or constrain each other’s orbits. In most cases, this results in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. Under some circumstances, a resonant system can be stable and self-correcting, so that the bodies remain in resonance. Examples are the 1:2:4 resonance of Jupiter‘s moons Ganymede, Europa and Io, and the 2:3 resonance between Pluto and Neptune. Unstable resonances with Saturn‘s inner moons give rise to gaps in the rings of Saturn. The special case of 1:1 resonance (between bodies with similar orbital radii) causes large Solar System bodies to eject most other bodies sharing their orbits; this is part of the much more extensive process of clearing the neighbourhood, an effect that is used in the current definition of a planet.”

iii. Some ‘work-blog related links’: Local regressionQuasi-experiment, Nonparametric regressionRegression discontinuity design, Kaplan–Meier estimator, Law of total expectation, Slutsky’s theorem, Difference in differences, Panel analysis.

iv. Wales in the Roman era.

v. Hill sphere.

“An astronomical body‘s Hill sphere is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit that lies within the planet’s Hill sphere. That moon would, in turn, have a Hill sphere of its own. Any object within that distance would tend to become a satellite of the moon, rather than of the planet itself.

In more precise terms, the Hill sphere approximates the gravitational sphere of influence of a smaller body in the face of perturbations from a more massive body. It was defined by the American astronomer George William Hill, based upon the work of the French astronomer Édouard Roche. For this reason, it is also known as the Roche sphere (not to be confused with the Roche limit). The Hill sphere extends between the Lagrangian points L1 and L2, which lie along the line of centers of the two bodies. The region of influence of the second body is shortest in that direction, and so it acts as the limiting factor for the size of the Hill sphere. Beyond that distance, a third object in orbit around the second (e.g. Jupiter) would spend at least part of its orbit outside the Hill sphere, and would be progressively perturbed by the tidal forces of the central body (e.g. the Sun), eventually ending up orbiting the latter. […]

The Hill sphere is only an approximation, and other forces (such as radiation pressure or the Yarkovsky effect) can eventually perturb an object out of the sphere. This third object should also be of small enough mass that it introduces no additional complications through its own gravity. Detailed numerical calculations show that orbits at or just within the Hill sphere are not stable in the long term; it appears that stable satellite orbits exist only inside 1/2 to 1/3 of the Hill radius.”

I found myself looking up quite a few other astronomy-related articles when I was reading Formation and Evolution of Exoplanets (technically the link is to the 2010 version whereas I was reading the 2008 version, but it doesn’t look as if a whole lot of stuff’s been changed and I can’t find a link to the 2008 version). I haven’t mentioned the book here because I basically gave up reading it midway into the second chapter. The book didn’t try to hide that I probably wasn’t in the intended target group but I decided to give it a try anyway: “This book is intended to suit a readership with a wide range of previous knowledge of planetary science, astrophysics, and scientific programming. Expertise in these fields should not be required to grasp the key concepts presented in the forthcoming chapters, although a reasonable grasp of basic physics is probably essential.” I figured I could grasp the key concepts even though I’d lose out on a lot of details, but the math started getting ugly quite fast, and as I have plenty of ugly math to avoid as it is I decided to give the book a miss (though I did read the first 50 pages or so).

vi. Grover Cleveland (featured).

Stephen Grover Cleveland (March 18, 1837 – June 24, 1908) was the 22nd and 24th President of the United States. Cleveland is the only president to serve two non-consecutive terms (1885–1889 and 1893–1897) and therefore is the only individual to be counted twice in the numbering of the presidents. He was the winner of the popular vote for president three times—in 1884, 1888, and 1892—and was the only Democrat elected to the presidency in the era of Republican political domination that lasted from 1861 to 1913.

Cleveland was the leader of the pro-business Bourbon Democrats who opposed high tariffs, Free Silver, inflation, imperialism and subsidies to business, farmers or veterans. His battles for political reform and fiscal conservatism made him an icon for American conservatives of the era.[1] Cleveland won praise for his honesty, independence, integrity, and commitment to the principles of classical liberalism.[2] Cleveland relentlessly fought political corruption, patronage, and bossism. Indeed, as a reformer his prestige was so strong that the reform wing of the Republican Party, called “Mugwumps“, largely bolted the GOP ticket and swung to his support in 1884.[3] […]

Cleveland took strong positions and was heavily criticized. His intervention in the Pullman Strike of 1894 to keep the railroads moving angered labor unions nationwide and angered the party in Illinois; his support of the gold standard and opposition to Free Silver alienated the agrarian wing of the Democratic Party.[5] Furthermore, critics complained that he had little imagination and seemed overwhelmed by the nation’s economic disasters—depressions and strikes—in his second term.[5] Even so, his reputation for honesty and good character survived the troubles of his second term. […]

Cleveland’s term as mayor was spent fighting the entrenched interests of the party machines.[46] Among the acts that established his reputation was a veto of the street-cleaning bill passed by the Common Council.[47] The street-cleaning contract was open for bids, and the Council selected the highest bidder, rather than the lowest, because of the political connections of the bidder.[47] While this sort of bipartisan graft had previously been tolerated in Buffalo, Mayor Cleveland would have none of it, and replied with a stinging veto message: “I regard it as the culmination of a most bare-faced, impudent, and shameless scheme to betray the interests of the people, and to worse than squander the public money”.[48] The Council reversed themselves and awarded the contract to the lowest bidder.[49] For this, and several other acts to safeguard the public funds, Cleveland’s reputation as an honest politician began to spread beyond Erie County.[50] […] [As a president…] Cleveland used the veto far more often than any president up to that time. […]

In a 1905 article in The Ladies Home Journal, Cleveland weighed in on the women’s suffrage movement, writing that “sensible and responsible women do not want to vote. The relative positions to be assumed by men and women in the working out of our civilization were assigned long ago by a higher intelligence.”[215]

Here’s how his second cabinet looked like – this was how a presidential cabinet looked like 120 years ago (as always you can click the image to see it in a higher resolution – and just in case you were in doubt: Cleveland is the old white man in the picture…):

800px-Cleveland_Second_Cabinet

vii. Boeing B-52 Stratofortress (‘good article’).

800px-Usaf.Boeing_B-52

“The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered strategic bomber. The B-52 was designed and built by Boeing, which has continued to provide support and upgrades. It has been operated by the United States Air Force (USAF) since the 1950s. The bomber carries up to 70,000 pounds (32,000 kg) of weapons.[4]

Beginning with the successful contract bid in June 1946, the B-52 design evolved from a straight-wing aircraft powered by six turboprop engines to the final prototype YB-52 with eight turbojet engines and swept wings. The B-52 took its maiden flight in April 1952. Built to carry nuclear weapons for Cold War-era deterrence missions, the B-52 Stratofortress replaced the Convair B-36. Although a veteran of several wars, the Stratofortress has dropped only conventional munitions in combat. Its Stratofortress name is rarely used outside of official contexts; it has been referred to by Air Force personnel as the BUFF (Big Ugly Fat/Flying Fucker/Fellow). […]

Superior performance at high subsonic speeds and relatively low operating costs have kept the B-52 in service despite the advent of later aircraft, including the cancelled Mach 3 North American XB-70 Valkyrie, the variable-geometry Rockwell B-1B Lancer, and the stealthy Northrop Grumman B-2 Spirit. The B-52 marked its 50th anniversary of continuous service with its original operator in 2005 and after being upgraded between 2013 and 2015 it will serve into the 2040s.[N 1] […]

B-52 strikes were an important part of Operation Desert Storm. With about 1,620 sorties flown, B-52s delivered 40% of the weapons dropped by coalition forces while suffering only one non-combat aircraft loss, with several receiving minor damage from enemy action.[1] […]

The USAF continues to rely on the B-52 because it remains an effective and economical heavy bomber, particularly in the type of missions that have been conducted since the end of the Cold War against nations that have limited air defense capabilities. The B-52 has the capacity to “loiter” for extended periods over (or even well outside) the battlefield, and deliver precision standoff and direct fire munitions. It has been a valuable asset in supporting ground operations during conflicts such as Operation Iraqi Freedom.[181] The B-52 had the highest mission capable rate of the three types of heavy bombers operated by the USAF in 2001. The B-1 averaged a 53.7% ready rate and the Northrop Grumman B-2 Spirit achieved 30.3%, while the B-52 averaged 80.5% during the 2000–2001 period.[160] The B-52’s $72,000 cost per hour of flight is more than the $63,000 for the B-1B but almost half of the $135,000 of the B-2.[182]

I’ll just repeat that: $72,000/hour of flight. And the B-2 is at $135,000/hour. War is expensive.

March 11, 2013 - Posted by | astronomy, biology, books, econometrics, history, Physics, wikipedia

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