Econstudentlog

Wikipedia articles of interest

i. British anti-invasion preparations of World War II. From the article:

“Any German invasion of Britain would have to involve the landing of troops and equipment somewhere on the coast, and the most vulnerable areas were the south and east coasts of England. Here, Emergency Coastal Batteries were constructed to protect ports and likely landing places. They were fitted with whatever guns were available, which mainly came from naval vessels scrapped since the end of the First World War. These included 6 inch (152 mm), 5.5 inch (140 mm), 4.7 inch (120 mm) and 4 inch (102 mm) guns. These had little ammunition, sometimes as few as ten rounds apiece. At Dover, two 14 inch (356 mm) guns known as Winnie and Pooh were employed.[25] There were also a small number of land based torpedo launching sites.[26]

Beaches were blocked with entanglements of barbed wire, usually in the form of three coils of concertina wire fixed by metal posts, or a simple fence of straight wires supported on waist-high posts.[27] The wire would also demarcate extensive minefields, with both anti-tank and anti-personnel mines on and behind the beaches. On many of the more remote beaches this combination of wire and mines represented the full extent of the passive defences.

Portions of the Romney Marsh, which was the planned invasion site of Operation Sea Lion, were flooded[28] and there were plans to flood more of the Marsh if the invasion were to materialise.[29]

Piers, ideal for landing of troops, and situated in large numbers along the south coast of England, were disassembled, blocked or otherwise destroyed. Many piers were not repaired until the late 1940s or early 1950s.[30]

Where a barrier to tanks was required, Admiralty scaffolding (also known as beach scaffolding or obstacle Z.1) was constructed. Essentially, this was a fence of scaffolding tubes 9 feet (2.7 m) high and was placed at low water so that tanks could not get a good run at it.[31] Admiralty scaffolding was deployed along hundreds of miles of vulnerable beaches.[32]

An even more robust barrier to tanks was provided by long lines of anti-tank cubes. The cubes were made of reinforced concrete 5 feet (1.5 m) to a side. Thousands were cast in situ in rows sometimes two or three deep.

The beaches themselves were overlooked by pillboxes of various types (see British hardened field defences of the Second World War). These were sometimes placed low down to get maximum advantage from enfilading fire whereas others were placed high up making them much harder to capture. Searchlights were installed at the coast to illuminate the sea surface and the beaches for artillery fire.[33][34][35]

I also thought this article, on British hardened field defences (pillboxes), was quite fascinating. It seems to me that at least a few of the models were not much more than poorly constructed deathtraps, whereas some others were remarkably well constructed.

ii. Bradford-Hill criteria. I was waiting a long time for these to be brought up (/mentioned?) during this lecture; they were never mentioned and along the way the lecturer made me start doubting whether he even knew the difference between a p-value and a correlation coefficient. Either way, the criteria are “a group of minimal conditions necessary to provide adequate evidence of a causal relationship between an incidence and a consequence” – here’s the list from the article:

  1. Strength of association (relative risk, odds ratio)
  2. Consistency
  3. Specificity
  4. Temporal relationship (temporality) – not heuristic; factually necessary for cause to precede consequence
  5. Biological gradient (dose-response relationship)
  6. Plausibility (biological plausibility)
  7. Coherence
  8. Experiment (reversibility)
  9. Analogy (consideration of alternate explanations)

Do have these in mind the next time you come across an article on reddit (or wherever) explaining how ‘drinking X two times a week will prevent cancer’ or how ‘doing Y will minimize your risk of getting disease Z’ (or whatever). Of course in 1965, when the criteria were formulated, people had never even heard about stuff like Granger causality tests, vector autoregressive models and instrumental variable models. Establishing any kind of reasonably strong argument for a causal relationship between two sets of variables is very hard.

iii. Minamata disease. Via mercury and mercury poisoning. It’s a horrible story and I think it’s pretty much certain that quite a few comparable disasters are unfolding right now elsewhere, e.g. in China. From the article:

Minamata disease […] is a neurological syndrome caused by severe mercury poisoning. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of vision and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death follow within weeks of the onset of symptoms. A congenital form of the disease can also affect foetuses in the womb.

Minamata disease was first discovered in Minamata city in Kumamoto prefecture, Japan, in 1956. It was caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation‘s chemical factory, which continued from 1932 to 1968. This highly toxic chemical bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Sea, which when eaten by the local populace resulted in mercury poisoning. While cat, dog, pig, and human deaths continued over more than 30 years, the government and company did little to prevent the pollution.

As of March 2001, 2,265 victims had been officially recognised (1,784 of whom had died)[1] and over 10,000 had received financial compensation from Chisso.[2] By 2004, Chisso Corporation had paid $86 million in compensation, and in the same year was ordered to clean up its contamination.[3] On March 29, 2010, a settlement was reached to compensate as-yet uncertified victims.[4]

A second outbreak of Minamata disease occurred in Niigata Prefecture in 1965. The original Minamata disease and Niigata Minamata disease are considered two of the Four Big Pollution Diseases of Japan.”

See also Patio process, a historically quite significant technique which improved the yields of silver mines in South America.

iv. Recovery position.

“The recovery position refers to one of a series of variations on a lateral recumbent or three-quarters prone position of the body, in to which an unconscious but breathing casualty can be placed as part of first aid treatment.

An unconscious person (GCS <8) in a supine position (on their back) may not be able to maintain an open airway as a conscious person would.[1] This can lead to an obstruction of the airway, restricting the flow of air and preventing gaseous exchange, which then causes hypoxia, which is life threatening. Thousands of fatalities occur every year in casualties where the cause of unconsciousness was not fatal, but where airway obstruction caused the patient to suffocate.[2][3][4] The cause of unconsciousness can be any reason from trauma to intoxication from alcohol.”

You never know when you need to know stuff like this.

v. Cassava.

Cassava (Manihot esculenta), also called yuca, mogo, manioc, mandioca and kamoting kaoy a woody shrub of the Euphorbiaceae (spurge family) native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy, tuberous root, a major source of carbohydrates. It differs from the similarly-spelled yucca, an unrelated fruit-bearing shrub in the Asparagaceae family. Cassava, when dried to a starchy, powdery (or pearly) extract is called tapioca, while its fermented, flaky version is named garri.

Cassava is the third-largest source of food carbohydrates in the tropics.[1][2] Cassava is a major staple food in the developing world, providing a basic diet for around 500 million people.[3] Cassava is one of the most drought-tolerant crops, capable of growing on marginal soils. Nigeria is the world’s largest producer of cassava.

Cassava root is a good source of carbohydrates, but a poor source of protein. A predominantly cassava root diet can cause protein-energy malnutrition.[4]

Cassava is classified as sweet or bitter. Like other roots and tubers, Cassava contains anti-nutrition factors and toxins.[5] It must be properly prepared before consumption. Improper preparation of cassava can leave enough residual cyanide to cause acute cyanide intoxication and goiters, and may even cause ataxia or partial paralysis.[6] Nevertheless, farmers often prefer the bitter varieties because they deter pests, animals, and thieves.[7] The more-toxic varieties of Cassava are a fall-back resource (a “food security crop”) in times of famine in some places.[8]

Using the toxic varieties as fall-back ressources is of course not exactly optimal. It can actually, and has, lead to really terrible outcomes (here’s the study Rosling talks about, I have not been able to find a non-gated version):

vi. Solon. I’m sure that for most readers the name rings a bell, but what do you actually know about the guy? If you click the link, you’ll know more…

vii. Emulsion.

“An emulsion is a mixture of two or more liquids that are normally immiscible (un-blendable). Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the continuous phase are liquid. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include vinaigrettes, milk, and some cutting fluids for metal working. The photo-sensitive side of photographic film is an example of a colloid.”

viii. Onomatopoeia. Included because that’s just a neat word for something I didn’t know had a name:

An onomatopoeia or onomatopœia […] from the Greek ὀνοματοποιία;[1] ὄνομα for “name”[2] and ποιέω for “I make”,[3] adjectival form: “onomatopoeic” or “onomatopoetic”) is a word that imitates or suggests the source of the sound that it describes. Onomatopoeia (as an uncountable noun) refers to the property of such words. Common occurrences of onomatopoeias include animal noises, such as “oink” or “meow” or “roar”. Onomatopoeias are not the same across all languages; they conform to some extent to the broader linguistic system they are part of; hence the sound of a clock may be tick tock in English, dī dā in Mandarin, or katchin katchin in Japanese.”

(And now you know…)

ix. Chemokine. It’s a technical article, but you can’t read it and not at least get the message that the human body is almost unbelievably complex.

 

May 18, 2012 - Posted by | biology, history, medicine, statistics, wikipedia

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