Month: August 2014

Wealth and religiosity disagree while some Hindus look the other way

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My extended family’s annual trip to Tirupati is coming up. Because a more indecisive bunch doth not exist, my relatives have been planning the trip for the last week. One creepy fact their discussions threw up is that, in 2013, the temple earned Rs. 220 crore from its sale of human hair. Pilgrims shave their heads at Tirupati as a token offering, and about 40 million people visit it annually. Although not all of them offer their hair, Rs. 220-crore’s worth must be a lot.

According to this PDF detailing the temple’s finances, the biggest chunk of its income comes from cash offerings from devotees, listed as ‘Kanuka’.

pie1

(All figures in Rs. crore)

Its other revenue receipts, including hair, are listed as such:

pie2

(All figures in Rs. crore)

Many of the world’s richest temples are in India. Some of the richest include the shrine at Shirdi, Maharashtra, for Sai Baba; the Padmanabhaswamy Temple, Thiruvananthapuram, Kerala; the Mahabodhi temple in Bodh Gaya, Bihar; and the Vaishno Devi temple in Jammu and Kashmir. Besides boasting overwhelming attendances, they’re also proof that Hinduism is a very materialistic religion when it comes to offerings despite its abstemious philosophies.

No matter this hypocrisy – the world at large rejects it anyway because religion and wealth share a negative relationship. Specifically, countries with higher GDP have lower religiosity. This document, wherefrom the religiosity numbers were pulled, defines religiosity as simply the fraction of people who identified themselves as religious in a survey.

gdprel

For planets, one thing leads to another

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One of the biggest benefits of being a journalist is that you become aware of interesting things from various fields. As a science journalist, the ambit is narrowed but the interestingness, not at all. And one of the most interesting things I’ve come across is a relationship between the rate at which planets rotate – the equatorial rotation velocity – and their mass. It seems the lighter the planet, the lower its equatorial rotation velocity. This holds true for all the planets in the Solar System, as well as large asteroids and Kuiper belt objects such as Pluto. The plot below shows logarithm of planet mass (kg) on the x-axis and logarithm of equatorial rotation velocity (km/h) on the y-axis.

The blue line running through the points is a local regression fit and represents a statistical connection. However, there are four prominent outliers. They represent Mercury, Venus, Earth and Mars, the System’s rocky, inner planets. Their spin-mass correlation deviates from the normal because they are close to the Sun, whose gravitational pull exerts a tidal force on the planets that slows them down. Earth and Mars are also influenced by the gravitational effects of their moons. Anyway, I’ve already written at length about this fascinating connection. What I want to highlight here are more such connections.

And before that, a note: it’s probably obvious that they exist because the connection between mass and equatorial velocity could just as well be a connection between mass and a string of other properties that eventually influence the equatorial velocity. This thought was what led me to explore more connections.

Mass and rotation period

The rotation period of a planet describes the time taken for the planet to rotate once around its axis. If mass and equatorial velocity are related, then mass and rotation period can be related, too, if there is a connect between mass and planetary radius, which in turn implies there is a connect between radius and density, which in turn implies that planets that can get only so big and so dense before they become implausible, presumably – a conclusion borne out by a study released on May 26.

Image: A log-log plot between planetary mass and rotation period.

Density and rotation period

If a planet can only get so big before it becomes puffy, and its mass is related to its rotation period, then its density and rotation period must be connected, too. The chart below shows that that hypothesis is indeed borne out (it’s not my hypothesis, FYI): log(density) increases as log(rotation period) does, so denser planets rotate faster. However, the plot shows significant variation. How do you explain that?

Image: A log-log plot between density and rotation period.

Turn to the Solar System’s early days. The Sun has formed and there is a huge disk of gas, rocks, dust and other debris floating around it. It exerts a gravitational pull that draws heavier things in the disk toward itself. As it becomes more energetic, however, it exerts a radiation pressure that pushes lighter things in the disk away. Thus, the outermost areas of the disk are mostly dust while the inner areas are heavier and denser. It’s possible that this natural stratification could have created different bands of material in the disk of different densities. These different kinds of materials could have formed different kinds of planets, each now falling on a specific part of the log(density) v. log(rotation period) plot.

Mass and density

Of course mass and density are related: the relation is called volume. But what’s interesting is that the volume isn’t arbitrary among the Solar System’s planets. It rises and then dips, which means heavier planets are less dense and, thus, more voluminous. For example, Jupiter is the heaviest planet in the Solar System – it weighs as much as 317 Earths. Its volume is more than 1,300-times Earth’s. However, its density – 1.33 g/cm3 versus Earth’s 5.52 g/cm3 – shouldn’t be surprising because it’s made of mostly hydrogen and helium. Which is just what we deduced based on the mass-period connection.

Image: A log-log plot between mass and density.

One way to find out if there’s any merit in this exercise is to conduct a detailed study. Another way is to perform a regression analysis. I’m not smart enough to do that, but I’ll blog in detail about that when I am.

Products of uranium-235 fission

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When I read, it’s always one thing leading to another. Someone tipped me off about a piece in Science about CTBT compliance monitoring efforts, and I ended up making this incredibly ghastly but satisfying mindmap of the product yield of uranium-235 fission by thermal neutrons. When August 29, the International Day Against Nuclear Tests, comes along and you want to make something for whatever, you could start with this.

u235fission

Science Quiz – August 4, 2014

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Every week, I create a science quiz for The Hindu newspaper’s In School product. It consists of 10 questions and only developments from the week preceding its day of publication (Monday). The answers are at the end.

But this week’s quiz is a little different. 2014 marks the hundredth year after the start of World War I, a global war that raged from 1914 to 1918. The scale of the conflicts provided an ample stage for the demonstration of the best technology of the time, albeit mostly for destructive purposes. This week’s quiz has 10 questions about that technology.

The British artillery in action during World War I.
Image: Wikimedia Commons
  1. World War I marked the first use of chemical weapons: At the Battle of Bolimov in Poland in January 1915, Germany released the gas xylyl bromide on the battlefield but it became harmless because of the cold. The first lethal use of chemical weapons was at the Second Battle of Ypres in Belgium in April 1915, when Germany used which yellow-green-colored gas to kill 6,000 French soldiers within 10 minutes?
  2. In response to the above attack, the American inventor James Bert Garner invented which simple device to protect combatants on the battlefield from inhaling poisonous gases? This device contained activated charcoal, which is a form of carbon that has a high surface area and absorbs many pollutants from the air. Later on, this device was developed for dogs as well as horses, and during World War II, was reinvented to be lighter and more effective.
  3. The Australian-British physicist William Bragg jointly won the Nobel Prize for physics in 1915 for using X-rays to study crystal structures. In the same year, the British assigned Sir Bragg to develop one of the world’s first scientific systems of sound ranging on the battlefield. What is sound ranging?
  4. The early 20th century saw the rise of industrialism and, along with it, the ________, a new form of motorized transport at the time. In January 1915, German and Ottoman forces set off to raid the Suez Canal. With help from Arab and Egyptian forces, the British advanced over the Sinai peninsula using the ________ to defend the canal. They also conquered the nearby area known as Palestine, an act that led to the later formation of the states of Israel, Lebanon, Syria and Jordan. Fill in the blank(s).
  5. The German inventor Ferdinand von ________ patented the design of a kind of airship, which have come to be named after him, in 1895. During World War I, they were used by the German army to bomb Britain, killing some 500. They then went out of service in 1919 after the defeat of Germany, but then reentered service in 1926 to fly people between Europe and North and South America. They would eventually be retired in the late 1930s and early 1940s. Name the inventor and the name of the airship it came to belong to.
  6. The first military use of __________ was in World War I. The British were reluctant to give their pilots these things because the British thought they would help cowardly pilots survive, effectively encouraging cowardice and reducing team morale. In July 1916, the American inventor Solomon Lee Van Meter, Jr., introduced the world’s first _________ that could be worn as a backpack, and had the revolutionary ripcord: a falling pilot need only pull the ripcord and the _________ would come into play and hopefully save the aviator’s life. Fill in the blank.
  7. The 1916 Battle of Jutland is well-known for being the only battle during World War I that was fought exclusively using _____, between the British and the Germans. At the time, it was only the third battle of its kind, the first two being fought during the Russo-Japanese War. By 1917, the Germans were numerically overwhelmed by the British and started attacking neutral resources in the vicinity, leading to the USA declaring war on Germany in the same year. Fill in the blank with another form of transport.
  8. The continuous metal track that had been developed in 1770 was bettered in the early 1900s. It consisted of a strip of metal plates bolted end-to-end that would run like a belt around two wheels. Such a mechanism was coupled with the four-stroke internal combustion engine, invented in the 1850s by Eugenio Barsanti and Felice Matteucci, to give rise to what extremely heavy, slow but very destructive weapon first used in World War I?
  9. During World War I, troops used to move in long, narrow ditches on the ground called trenches, which protected them from above-ground attacks by enemy troops. To counter this protection, the Germans developed a weapon they created two versions of, called the Kleinflammenwerfer and the Grossflammenwerfer. They were first used in July 1915, and very effectively. When fired into trenches, their effect would flush out British and French troops. Their principal mechanism was to channel oil through a rubber tube and toward a wick. What does Flammenwerfer translate to in English?
  10. The first light, or portable, _______ ___ was developed by the Americans. It was the first of its kind that could be operated by just one man. It was adapted by the British army, and its use was decisive during the Battle of Hamel in France in July 1918, where it reduced the battle time from a potential weeks or months to less than two hours. Fill in the blank.

Answers

  1. Chlorine
  2. Gas mask
  3. Using the sound of firing guns to locate where the guns are using sensors like microphones
  4. Railways
  5. Zeppelin
  6. Parachutes
  7. Ships
  8. Tanks
  9. Flamethrower
  10. Machine gun

Keeping up with the radioxenons

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After the first of two nuclear weapon tests by North Korea, in 2006, a monitoring station in Yellowknife, Canada, caught a whiff of xenon-133, a radioactive isotope of xenon, in the atmosphere. It had been released by the blast and had traveled more than 7,500 km. Being a noble gas, it hadn’t reacted to anything on the way.

The Yellowknife station is part of the International Monitoring System installed by the Comprehensive Test Ban Treaty Organization (CTBTO), which ensures signatory countries’ compliance with the treaty that prohibits them from testing nuclear weapons. In early July 2014, the organization signed a pact with an American company named NorthStar, which manufactures radioactive isotopes for medical diagnostics. The pact was signed because, as it turns out, radioxenon is also a by-product of the manufacture of substances used in medical diagnostics, and NorthStar was agreeing to deliberately limit its emission to help the IMS facilities focus on radioxenon from nuclear weapon tests alone.

In anticipation of August 29 being the International Day against Nuclear Tests, here’s a breakdown of the life and times of xenon-133 and xenon-135, two radioactive isotopes of xenon that serve as proxies for uranium irradiation.

The 18,000 sq. km. expanse of the Semipalatinsk Test Site (indicated in red), the Soviet Union's test-bed of choice. It was shut on August 29, 1991. The date was chosen as the International Day against Nuclear Tests by the UN.

Image: The 18,000 sq. km. expanse of the Semipalatinsk Test Site (indicated in red), the Soviet Union’s test-bed of choice. It was shut on August 29, 1991. The date was chosen as the International Day against Nuclear Tests by the UN. Image: Wikimedia Commons

What happened during the 2006 nuclear tests by North Korea?

North Korea’s first nuclear test was conducted in October 2006. While CTBTO-installed seismographs picked up the underground shockwaves, that a nuclear explosion occurred was further certified by the Yellowknife atmospheric radionuclide detection station in Canada two weeks after the blast. On the other hand, no radioxenon was detected after the May 2009 nuclear test also by North Korea.

How do xenon-133 and xenon-135 show up in nuclear detonations in the first place?

Xenon-135 is a decay product of iodine-135, which itself is an important fission product of uranium-235. Iodine-135 has a half-life of 6.7 hours and is also produced by the radioactive decay of tellurium-135. As a result, radioxenon is continuously produced during a fission reaction and can thus “poison” a reactor. This happens because xenon-135’s neutron-absorbing capacity is more than 5,000 times that of uranium-235. So during a fission reaction, the radioxenon can remove the slow-moving trigger neutrons from the fray, reducing the reaction rate. For some reason, this event is called a “poisoning”. The mismanagement of a similar “poisoning” event was what led to the 1986 Chernobyl disaster.

How much radioxenon is released from a nuclear weapon explosion?

When xenon-135 absorbs a neutron, it turns into xenon-136. When it doesn’t, it decays into cesium-135, a long-lived isotope (with a half-life of 2.3 million years).

According to a 2012 thesis submitted at the Third University of Rome, the energy from a fission blast is roughly split as:

blast

  • 50% for air blast and shock waves,
  • 35% for thermal radiation,
  • 15% in ionizing radiation

The last 15% is split as 5% in the form of neutrons and gamma rays, and 10% in the form of beta and gamma radiation over time. A one-kiloton blast produces about 1.08-1.33 x 1016 becquerel of radioactive xenon-133. This number is important because it could inform scientists attempting to estimate radioxenon amounts based on the number of treaty-approved reactors in ratifying nations, together with the observation records shared by its compliance monitoring facilities. A 2009 study in the Journal of Environmental Radioactivity estimated that 1.3 peta-becquerel of radioxenon escaped each year from nuclear reactors.

What happens to the radioxenon after a nuclear weapon explosion?

Nuclear weapons can be detonated in four ‘places’: underground, in the atmosphere, in space, and underwater. When a nuclear weapon goes off in the atmosphere, it’s assumed that all the noble gas isotopes are released into the atmosphere and not deposited on the ground below. In an undersea blast, it’s thought that xenon-135 rises up through the water and enters the atmosphere. Space-based blasts can be ignored for now, leaving the underground explosion which is also the trickiest to study.

Four 'places' nuclear weapons can be tested in.

 

Image: Four ‘places’ nuclear weapons can be tested in. Image: Wikimedia Commons

From the Third University of Rome thesis,

The released energy leads to an increase in pressure and temperature, which are transmitted into the surrounding, and an isotropic shock wave is created. Milliseconds after the detonation the outward directed pressure and shock wave create an underground cavity. The inside wall of the cavity is coated with fused earth, but since the inside of the cavity is pressurized the surrounding walls are likely to get fractured. When gas is leaking through these cracks, the pressure decreases and rubble can fall down. By repeating this the cavity can migrate towards the surface. The shifting of earth material downwards can cause a crater to be formed on the surface. The amount of gas that leaks through the earth to the surface can vary widely. It can hardly be predicted,  because it depends on many parameters such as the rock composition and depth, yield and kind of explosion.

Based on these conditions and calculations on detonations at the Nevada Test Site, xenon-135 is thought to leak to the surface in meaningful quantities in about three hours after an underground blast. At the same time, it’s not unlikely that the detonators have taken precautions and sealed off the site to prevent gases from escaping. This is what is thought to have happened after the 2009 North Korea test.

How is a radioxenon correlated with a nuclear blast?

The CTBTO has installed a worldwide ‘International Monitoring Station’ that’s actually a composite of 337 monitoring facilities. Out of them, 80 are on the lookout for radionuclides, and of them, 40 can detect radioxenon. The map below shows their locations. When a nuclear weapon goes off and radioxenon gets into the atmosphere, the stations closest to the blast, as well as those in the way of the winds that carry it, can pick it out.

ctbtmap

 

Why choose to track radioxenon and not anything else?

Xenon-135 has a half-life of 9.14 hours, which means it’s around long enough for it to be spotted in the atmosphere, but not long enough so that its presence masks more recent emissions. Second, it’s noble, i.e. chemically inert. Third, xenon-133 and xenon-135 are produced in significant quantities – some 5-7% of total emissions – in the aftermath of a nuclear explosion. Fourth, xenon-133 and xenon-135 are not produced naturally.

How is radioxenon formed during the production of medical isotopes?

Technetium-99 is an isotope used ubiquitously in medical diagnostics, and it is formed by the radioactive decay of molybdenum-99. The way to get molybdenum-99 is through an arduous irradiation and filtration of uranium-235.

First, uranium is sandwiched between two aluminum plates and bombarded with neutrons at something like 10 trillion to 500 trillion neutrons per squared centimeter per second for two or more days. Then, the uranium is left to cool for a day to remove short-lived isotopes that the irradiation would’ve yielded. Next, the important fission products are removed by dissolving the uranium in hot acid – and this is when radoi xenon is produced, being subsequently isolated and released into the atmosphere. Once they’re out of the way, the molybdenum-99 can be filtered out.

Is there any way to say where some radioxenon has come from – a nuclear blast or a medical isotope purification facility?

Unfortunately, no. Whether it’s xenon-133 or xenon-135, their atoms don’t carry signatures of their source as much as they signify that uranium has been irradiated and that it has subsequently decayed. This is where pacts like those between the CTBTO and NorthStar come in. Without deliberated control of their release from medical facilities, they could just as well mask the release of radioxenon from nuclear explosions, or from previously unaccounted-for nuclear reactors. So just as their absence doesn’t preclude the occurrence of a nuclear explosion, their presence doesn’t imply one either – an obvious hindrance to the smooth monitoring of compliance to the CTBT.

~

References

  1. Brumfiel, G., North Korea’s ignoble blast, Nature, June 16. doi:10.1038/news.2009.575
  2. Schöppner, M., Analysis of the Global Radioxenon Background with Atmospheric Transport Modelling for Nuclear Explosion Monitoring, Third University of Rome, 2012. Accessed August 2, 2014
  3. Kalinowski, M.B. & Tuma, M.P., Global radioxenon emission inventory based on nuclear power reactor reports, J. Environ. Radioact., Jan 2009, 58-70. doi: 10.1016/j.jenvrad.2008.10.015
  4. Annual Report, CTBTO Preparatory Commission, 2012. Accessed August 2, 2014
  5. Xenon-135 Response to Reactor Power Changes, nuclearpowertraining.tphub.com. Accessed August 2, 2014
  6. Roggenkamp, P.L., The Influence of Xenon-135 on Reactor Operation, WSRC-MS-2000-00061. Accessed August 2, 2014

Hat-tip to S.V.

Plotting transmission losses

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Transmission loss in GWh in India. Data from Central Electricity Authority. Click on the image for hi-res version. All data available here.

transmission loss v. year

Transmission loss as % of net generation in GWh. Net generation = Gross generation — consumption by auxiliary power plant unitstransmission loss as of net generation in GWh

(Model used to fit: LOESS)

Rise of net supply to ultimate consumers and exports v. purchase of power from non-utilities and imports before transmission. Note different y-axes: net supply, right; purchase, left; both in GWh

purcsupp