Econstudentlog

Wikipedia articles of interest

1. Tuberculosis. I linked to it in a different post a while ago, but that post had a lot of links so people probably weren’t paying much attention at that point and/or following the link. Some highlights from the article:

“Tuberculosis, MTB, or TB (short for tubercle bacillus) is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis.[1] Tuberculosis usually attacks the lungs but can also affect other parts of the body. It is spread through the air when people who have an active MTB infection cough, sneeze, or otherwise transmit their saliva through the air.[2] Most infections in humans result in an asymptomatic, latent infection, and about one in ten latent infections eventually progress to active disease, which, if left untreated, kills more than 50% of those infected. […]

One third of the world’s population is thought to have been infected with M. tuberculosis,[3][4] and new infections occur at a rate of about one per second.[3] In 2007 there were an estimated 13.7 million chronic active cases,[5] and in 2010 8.8 million new cases, and 1.45 million deaths, mostly in developing countries.[6] […] The distribution of tuberculosis is not uniform across the globe; about 80% of the population in many Asian and African countries test positive in tuberculin tests, while only 5–10% of the U.S. population test positive.[1] […]

Tuberculosis caused the most widespread public concern in the 19th and early 20th centuries as an endemic disease of the urban poor. In 1815, one in four deaths in England was of consumption; by 1918 one in six deaths in France were still caused by TB. After the establishment in the 1880s that the disease was contagious, TB was made a notifiable disease in Britain; there were campaigns to stop spitting in public places, and the infected poor were “encouraged” to enter sanatoria that resembled prisons; the sanatoria for the middle and upper classes offered excellent care and constant medical attention.[84] Whatever the purported benefits of the fresh air and labor in the sanatoria, even under the best conditions, 50% of those who entered were dead within five years (1916).[84] […]

It was not until 1946 with the development of the antibiotic streptomycin that effective treatment and cure became possible. Prior to the introduction of this drug, the only treatment besides sanatoria were surgical interventions, including the pneumothorax technique—collapsing an infected lung to “rest” it and allow lesions to heal—a technique that was of little benefit and was largely discontinued by the 1950s.[90] The emergence of multidrug-resistant TB has again introduced surgery as part of the treatment for these infections. Here, surgical removal of chest cavities will reduce the number of bacteria in the lungs, as well as increasing the exposure of the remaining bacteria to drugs in the bloodstream, and is therefore thought to increase the effectiveness of the chemotherapy.[91]”

In completely unrelated news…

2. Nitrogen cycle. A couple of images from the article:

3. Bazooka. Lots of stuff I didn’t know. Here’s an interesting bit:

“A major disadvantage to the bazooka was the large backblast and smoke trail (in colder weather), which gave away the position of the shooter, mandating quick relocation of the squad. Moreover, the bazooka fire team often had to expose their bodies in order to obtain a clear field of fire against an armored target. Casualties among bazooka team members were extremely high during the war, and assignment to such duty, widely known as Medal of Honor work in the face of German counterfire was typically regarded by other platoon members as not only highly dangerous, but nearly suicidal.”

4. Coal. Some stuff from the article:

“About 300 million years ago, the earth had dense forests in low-lying wetland areas. Due to natural processes, like flooding, these forests got buried under the soil. As more and more soil deposited over them, they were compressed. The temperature also rose as they sank deeper and deeper. For the process to continue, the plant matter was protected from biodegradation and oxidization, usually by mud or acidic water. This trapped the carbon in immense peat bogs that are eventually covered and deeply buried by sediments. Under high pressure and high temperature dead vegetation got slowly converted to coal. As coal contains mainly carbon, the conversion of dead vegetation into coal is called carbonization.[4]

The wide shallow seas of the Carboniferous period provided ideal conditions for coal formation, although coal is known from most geological periods. The exception is the coal gap in the Lower Triassic, where coal is rare: presumably a result of the mass extinction which prefaced this era. Coal is known from Precambrian strata, which predate land plants: this coal is presumed to have originated from algal residues.[5][6] […]

In 1700, 5/6 of the world’s coal was mined in Britain. Without coal, Britain would have run out of suitable sites for watermills by the 1830s.[21] In 1947, there were some 750,000 miners,[22] but by 2004 this had shrunk to some 5,000 miners working in around 20 collieries.[23] […]

When coal is used for electricity generation, it is usually pulverized and then combusted (burned) in a furnace with a boiler.[28] The furnace heat converts boiler water to steam, which is then used to spin turbines which turn generators and create electricity. The thermodynamic efficiency of this process has been improved over time. Simple cycle steam turbines have topped out with some of the most advanced reaching about 35% thermodynamic efficiency for the entire process. Increasing the combustion temperature can boost this efficiency even further.[29] Old coal power plants, especially “grandfathered” plants, are significantly less efficient and produce higher levels of waste heat. At least 40% of the world’s electricity comes from coal,[28][30] and in 2008 approximately 49% of the United States’ electricity came from coal.[31] […]

For a coal power plant with a 40% efficiency, it takes 325 kg (714 lb) of coal to power a 100 W lightbulb for one year.[60] […]

Of the three fossil fuels, coal has the most widely distributed reserves; coal is mined in over 100 countries, and on all continents except Antarctica. The largest reserves are found in the USA, Russia, China, India and Australia.”

5. Acanthochronology. File under: ‘You almost certainly did not know that this field of inquiry even existed.’

6. Japanese aircraft carrier Shinano.

“Shinano […] was an aircraft carrier of the Imperial Japanese Navy during World War II. Initially laid down as the third of the Yamato-class battleships, Shinano’s partially complete hull was converted to an aircraft carrier in 1942, midway through construction. Over the next two years, Shinano was heavily modified to act as a large support carrier. When completed, she had a full-load displacement of 72,000 long tons (73,000 t), the largest aircraft carrier ever built at the time.

Commissioned in November 1944, Shinano was to transfer from the Yokosuka Naval Shipyard to Kure Naval Base to complete her outfitting and transfer a load of 100 Yokosuka MXY7 Ohka rocket-propelled kamikaze aircraft. While en route, Shinano was sunk by the American submarine USS Archer-Fish 10 days after her commissioning — the result of severe design flaws, crew inexperience and poor damage control. To date, she is the largest warship to be sunk by a submarine.”

Some more details:

“On 19 November 1944, Shinano was formally commissioned at Yokosuka, having spent the previous two weeks fitting out and performing minor trials.[6] By 1 October the crew had reported on board, 70 to 75 percent of which had no previous sea duty experience.[7] As a result of growing worry for her safety, due to a U.S. bomber fly-over, Japanese Naval Command ordered Shinano to Kure, where the remainder of her fitting-out would take place.[6] Naval Command wanted Shinano moved to Kure no later than 28 November. However, Abe asked for a delay in the sailing date. The majority of her watertight compartment doors had yet to be installed, the compartment air tests had not been conducted, and many holes for electrical cables, ventilation ducts and pipes had not been sealed.[3] Nor had the fire mains or drainage systems been completed as pumps had not been delivered.[7] He also wanted more time to train his new crew, and to give the crews of the destroyers a rest after returning from battle.[5]

Abe’s request was denied” (…so Abe ended up dead at the bottom of the ocean, just like 1,434 others)

7. South Pole–Aitken basin. It turns out that one of the largest known impact craters in the Solar System is to be found on the moon. I did not know that. It’s pretty damn big: “Roughly 2,500 kilometres (1,600 mi) in diameter and 13 kilometres (8.1 mi) deep. […] The South Pole-Aitken basin is the largest, deepest and oldest basin recognized on the Moon.[1] The lowest elevations of the Moon (about -6 km) are located within the South Pole-Aitken basin, and the highest elevations (about +8 km) are found on this basin’s north-eastern rim. Because of this basin’s great size, the crust at this locale is expected to be thinner than typical as a result of the large amount of material that would have been excavated during this impact event. Crustal thickness maps constructed using the Moon’s topography and gravity field imply a thickness of about 15 km beneath the floor of this basin, in comparison to the global average of about 50 km.[4]”

8. Columbian Exchange.

March 25, 2012 - Posted by | astronomy, biology, Geology, health, history, medicine, wikipedia

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