E2science

This node will look briefly at the three types of oils: essential, fixed, and mineral oils, before going on to look at petroleum or crude oil in more depth. Drilling and refining oil will be described, followed by a discussion of political aspects of oil production in the world economy.

There are three main types of oils. Essential oils are obtained from plants, and have the odour of their plant source. They are often used in perfumes, flavourings, and aromatherapy. Fixed oils are obtained from animals and plants, and are mixtures of lipids, used as foods and lubricants and in making soaps, paints, and varnishes. Mineral oils are hydrocarbons used as fuels and lubricants and are mainly obtained by refining petroleum.

Petroleum or crude oil is a thick greenish-brown liquid found in permeable underground rock, and consisting mainly of hydrocarbons and mixed with other elements, especially oxygen, sulphur, and nitrogen. Petroleum is believed to have been formed from the remains of ancient living organisms deposited with rock-forming sediments. These have then been converted by the effects of heat, pressure, and bacterial action, and changed into petroleum. This liquid then migrated through porous rocks and fissures, becoming trapped in large underground reservoirs.

In order to locate and drill for oil, geologists first look for variations of rock density in the type of rocks where oil is known to occur. Exploratory drillings then confirm the presence of oil. Oil wells are made by drilling with a rotating bit supported in a wider shaft. A special mud is then pumped through the hollow bit to collect debris, which is forced back up the shaft around the drilling bit.

Petroleum is refined by a process known as fractional distillation, where components are separated according to their boiling points. The distillation fractions are then blended, producing products like fuel oil, petrol (gasoline), kerosene, diesel, and lubricating oil. Other processes such as catalytic cracking are used to increase the yield of petrol and reduce the viscosity of heavier oils. These processes lead to valuable petrochemicals used in detergents, plastics, and drugs.

Worlwide dependence on oil has led to many attempts to control production levels and prices. The US drilled the first commercial well in Pennsylvania in 1859, and led in production until the 1960s when Middle Eastern reserves led to cheap oil and worldwide dependence. The Organisation of Petroleum Exporting Countries (OPEC) was formed in 1961 to protect member countries from exploitation. OPEC introduced price rises in 1973, and in 1974 the International Energy Agency (IEA) was formed to protect the interests of oil-consuming countries. North Sea oil and the Alaska pipeline have helped stabilise prices since then, but wars in Iran, Iraq, and Kuwait have heightened fears about unstable production levels. World oil reserves and future consumption are both difficult to estimate accurately.

The environmental impact of oil disasters cannot be overlooked. These disasters are some of the world's worst environmental catastrophes, and include the Torrey Canyon, Amoco Cadiz, and Exxon Valdez tanker spills, and the oil wells destroyed in Kuwait and Iraq in the Gulf War.

In summary, then, the impact of oil on the world's economy and the lives of individuals is a very important one, and one which has led to many attempts to gain control over oil production and prices.

A stone baby, or lithopedion, results when a fetus dies during an ectopic (typically abdominal) pregnancy, is too large to be reabsorbed by the body, and calcifies. It is not unusual for a lithopedion to remain undiagnosed for decades, and it is often not until a patient is examined for other conditions that a stone baby is found. The oldest reported case is that of a 94 year old woman, whose lithopedion had probably been present for over 60 years.

Lithopedion is a rare phenomenon, occurring once in about 20 000 pregnancies, and with less than three hundred cases noted in medical literature accumulated over some 400 years. Lithopedion may occur from 14 weeks' gestation to full term. The earliest stone baby is one found in an archaeological excavation, dated to 1100 BCE.

A related condition is known as fetus papyraceus, in which the fetus is one of two or more sharing the womb. If the fetus is older than eight weeks at the time of its death, and is retained in the uterus for at least ten weeks, it may undergo mechanical compression such that it takes on a flattened, mummified appearance and resembles parchment paper.

Further reading

CAUTION: GRAPHIC IMAGES

OBGYN Net =>http://www.obgyn.net/ENGLISH/PUBS/ARTICLES/Stone_Baby.htm
PubMed (enter 'lithopedion' in search box) => http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=Search&DB=PubMed

This writeup has also appeared in Wikipedia® http://en.wikipedia.org

Carbon-14 is an isotope of carbon that is found naturally in our atmosphere. It is radioactive, and is best known because it collects in biological entities while they are living. Once the plant or animal dies, it stops taking in new carbon-14 and the carbon-14 it has starts decaying. By measuring the amount of carbon-14 left in the remains you can judge their age.

Carbon-14 is formed when radiation in the from of cosmic rays enters the atmosphere. Gamma radiation produces free neutrons, which fly about looking for a home. They often come to rest in a nitrogen atom, pushing out one of the protons and replacing it. Thus a typical nitrogen atom (seven protons and seven neutrons) becomes an atypical carbon atom (six protons and eight neutrons), giving it an atomic mass of 14, instead of the usual 12.

Although carbon-14 is produced primarily in the upper troposphere, it continuously disperses throughout the atmosphere. Along the way it joins with oxygen, as carbon will, to produce carbon dioxide. Plants take in this carbon dioxide, and the carbon is used in biological molecules of all sorts. Animals that eat these plants, and animals that eat the animals that eat these plants, pick up the carbon-14 and use it in their own bodies.

Once the plants or animals die, they stop taking in new building blocks (including carbon and carbon-14), and the carbon-14, being unstable, starts to decay. Carbon-14 in the atmosphere is also decaying continuously, of course, but this isn't so useful to us. Carbon-14 has a half-life of 5730 ± 40 years, so measuring the proportion of carbon-14 in a historical sample to the proportion of carbon-14 in a modern sample can give a good indication of the historical sample's age. Samples over the age of about 40,000 years have too little carbon-14 left to be of much use in dating them. Carbon-14 decays through beta decay (beta minus decay), in which one of the neutrons breaks down into a proton, an electron, and an anti-neutrino. The latter shoots off into the wild blue yonder, but the others stay and we once again have a typical nitrogen atom (nitrogen-14).

Carbon-14 can also be produced through other radiation related processes, both in the upper atmosphere and in laboratories, although these are minor sources. Recently the amount carbon-14 in the atmosphere spiked, as the radiation from nuclear testing in the 1940s, 50s, and 60s created excess amounts of carbon-14. This has the potential to mess up future carbon dating, but is otherwise harmless (there are some cases where this excess carbon-14 actually helps dating, as tooth enamel gives an exact record of how much carbon-14 was in the air at the specific time it was formed). Carbon dating is covered in its own node, but it is worth noting that the production of carbon-14 is not stable over time, and thus all carbon dating has some additional wiggle room on top of the statistical uncertainty of half-life predictions (the ± 40 years above). This has caused many archeologists and paleontologists major head aches, and is one of the reasons why scientists try to look at more than one method of dating.

Carbon-14 is, even after nuclear testing, only a very very very small part of our atmosphere, about 0.0000000001% of the carbon present on Earth.

Carbon-13 is a stable isotope of carbon, and is useless in carbon dating. It is apparently formed in the interior of stars, as is typical carbon, carbon-12. It has nothing to do with carbon-14, and was only included here because I was curious.

This is one of the tiniest bones in the body. You have two of them, right at the inner corners of your eyes. Where tears come out. (The technical term for crying is lacrimation. You see the resemblance.)

The lacrimal bone is part of the orbital socket. It articulates with four other bones: the frontal, ethmoid, maxilla, and inferior nasal concha.

The lateral or orbital surface is divided into two parts by a crest. One side of the crest forms part of the orbital socket (yes, that's the part touching your eye right now). The front side of the crest has a groove in it. That's the lacrimal sulcus, and it fits with part of the maxilla to form the lacrimal fossa.

That crest ends in a hook, the lacrimal hamulus. It too articulates with the maxilla, forming the upper end of the nasolacrimal canal. Sometimes the hook is a separate bone (that would then be the tiniest bone in your body) and that's called the lesser lacrimal bone.

The medial surface has a long groove on it—the other side of that crest. The back part articulates with the ethmoid bone, and the front part forms part of your nasal cavity.

You will never need to know about this bone. When I studied osteology, it was mentioned and we saw one, but it wasn't on the exam. But I'm glad I know it's there, this little tiny thing named for tears.

If you would like to see one, the drawings from Gray's Anatomy are in the Wikipedia article on the lacrimal bone. A simple Google image search will also turn up several.

Sources

http://en.wikipedia.org/wiki/Lacrimal_bone
Anthropology 451 Osteology at the University of Victoria

BrevityQuest07

To the general public, the most visible part of the particle physics world is the vast particle accelerator complexes where physicists push the energy frontier, places such as Fermilab and CERN. Despite the importance and expense of these machines, some of the most important particle physics results of the last decade have come from a 50,000 ton tank of water in the mountains of Honshu named Super-Kamiokande. Super-K, as it is commonly called, is the world's largest water Cerenkov detector, which observes fast-moving subatomic particles through the radiation they produce when moving faster than the speed of light in water. Super-K is generally used to detect neutrinos, where the water Cerenkov detector allows particles to be detected right from the point where they are produced by the interaction of a neutrino, and it is in this field of particle physics where its most famous results have occurred.

History of Super-Kamiokande

As can be guessed from the form of the name, Super-K is the successor to an earlier, smaller detector, the KamiokaNDE (sic) detector. KamiokaNDE was originally designed to study a completely different problem: proton decay. Many of the grand unified theories proposed in the early 1980's predicted that the familiar proton, building block of atoms, was not absolutely stable as it is in the Standard Model of particle physics, but rather decays with a very long half-life. This half-life was predicted to be much longer than the age of the universe: about 10³⁰ years, or 10²⁰ times the age of the universe.

Detecting such a slow process would seem to be impossible, given that we don't have 10³⁰ years to wait. However, the sheer prevalence of protons allows us to short-circuit this waiting process. A gram of water contains about 10²⁶ protons, so we would expect one of them to decay every 10,000 years or so. Given the vast quantities of water on the face of the Earth, we can get together enough to see one proton decay a year, or tens, or hundreds, even with a 10³⁰ year lifetime. Thus, KamiokaNDE (Kamioka Nucleon Decay Experiment) was born. 1,000 tons of pure water, containing 10³⁵ protons, was placed in a tank under a mountain in Japan, near the town of Kamioka (now part of Hida city) and instrumented to look for the Cerenkov light of the proton's (much lighter) decay products.

The underground location was chosen so that cosmic rays would not light up the sensitive detector with their near-lightspeed passage, but would instead stop in the dense rock above the detector. This shield, though it would be very effective in stopping muons and electrons from cosmic rays, did not stop the neutrinos produced by cosmic rays striking the atmosphere, known as 'atmospheric neutrinos'. These neutrinos would strike nuclei in the water and produce muons which then in turn produce a detector event, making these neutrinos a significant source of background for the proton decay measurement.

KamiokaNDE didn't see proton decay, and neither have any of the other experiments that have gone looking for it. This is an important measurement in itself, as the lower limit found for the proton lifetime has ruled out many of the grand unified theories that motivated the construction of KamiokaNDE. It was KamiokaNDE's background measurements, though, that motivated the construction of its successor. Its measurement of the atmospheric muon neutrino flux was significantly below predictions, leading to an 'atmospheric neutrino problem' parallel to the more famous Solar Neutrino Problem. KamiokaNDE also contributed to the Solar Neutrino Problem by being the first detector to determine that the presumed 'solar' neutrinos were coming from the direction of the Sun, the previous detectors of solar neutrinos having no sensitivity to the direction of the incoming neutrino. Furthermore, KamiokaNDE pioneered neutrino astronomy by observing the burst of neutrinos from Supernova 1987A, leading to further experiments intended to study supernova neutrinos and try to elucidate the role of neutrinos in supernova explosions.

Super-Kamiokande was designed primarily as an atmospheric neutrino detector, though it doubled as a next-generation proton decay experiment. 50 times the volume of KamiokaNDE, Super-K has a much greater target mass as well as greater sensitivity.

The Super-K Detector

The core of Super-K is a cylindrical acrylic water tank filled with 50,000 tons of purified water. This tank is 41m tall and is 39m in diameter. The inner surfaces of the tank are instrumented with 11,000 sensitive photomultiplier tubes, which detect the Cerenkov light from particles in the detector. The complex is buried under 1 km of rock as shielding from the overwhelming background of cosmic rays.

Most neutrino interactions involve the neutrino transforming through the weak nuclear force into an electron or muon, retaining much of its energy. While electrons and muons are reasonably similar particles, the greatly different mass of the two particles causes them to appear quite different in the Super-K detector. The heavy muons move very close to straight through the detector, which given the cone shape of the Cerenkov radiation makes a sharp, well-defined ring of light on the surface of the detector. Electrons, on the other hand, bounce around in the matter, giving a much fuzzier ring. In this way, Super-K can determine whether the incident neutrino is a muon or electron neutrino, which is an important measurement for finding and characterizing neutrino oscillation.

To fully determine the energy of the particle, it is necessary that it both originate and stop within the volume of the detector. As such, an additional 2,000 phototubes were placed in the detector facing outwards, so as to see the passage of high-energy particles as they enter and leave. This 'outer detector' is a common feature of many neutrino detectors, large and small, allowing much better rejection of background events.

Experimental Achievements of Super-K

Super-K began taking data in 1996, and had its first major results available for the Neutrino98 conference in 1998. These results were the first clear evidence for neutrino oscillations and were based on measurements of atmospheric neutrinos produced at different points on the Earth. Since the neutrinos travelling upwards through the Earth into Super-K have travelled much further since being produced than the neutrinos travelling straight downwards into Super-K, they will have had more time to oscillate and thus are less likely to appear as muon neutrinos. As such, the expectation was that there would be fewer up-going muon neutrinos than down-going muon neutrinos, and this is exactly what Super-K observed.

Super-K continued to record atmospheric neutrino data until disaster struck in November 2001. Approximately six thousand of the photomultiplier tubes imploded in a disastrous chain reaction, with each of the implosions producing a shock wave in the detector water that in turn produced further implosions. The loss of half of the photosensors halved the detector's sensitivity, necessitating the replacement of the broken tubes for resumption of atmospheric and solar neutrino detection.

The remaining unbroken phototubes were distributed evenly over the surface of Super-K, making the Super-Kamiokande II detector. This was primarily for the use of the K2K experiment, which used a beam of high-energy neutrinos produced at the KEK particle accelerator 250 km away in Tsukuba. K2K was the first experiment to use an artificial neutrino beam from a particle accelerator, all previous studies of artificial neutrinos being made using nuclear reactors. Given the known direction, energy, and timing of the K2K neutrinos, the reduced sensitivity of Super-K II was not a major obstacle to the re-observation of neutrino oscillations with the K2K beam. In 2005 and 2006 the broken phototubes were gradually replaced, with the fully-restored detector coming online in June 2006 as Super-Kamiokande III.

The Future of Super-K

Beyond refining its previous measurements, Super-K has a major part to play in the further development of neutrino physics. The T2K experiment is the successor to K2K, planned to begin operation in 2009. A much higher-intensity beam from the new J-PARC accelerator in Tokai will be sent over 295 km to Super-K, with the initial goals of making a precision measurement of the muon neutrino survival probability and a first measurement of electron neutrino appearance in a muon neutrino beam. (Previous experiments have only observed a deficit of muon neutrinos which are assumed to have oscillated mainly into tau neutrinos.)

T2K should occupy Super-K's resources for many years to come, especially if a proposed beam upgrade extends its experimental programme. However, plans for a successor detector, dubbed Hyper-Kamiokande, have been suggested. Hyper-K would consist of two 500,000 ton water Cerenkov detectors, whose improved sensitivity would improve both atmospheric neutrino and T2K results, at the same time as the increased mass increased sensitivity to proton decay. Not only are two half-megaton detectors considered more economical than a single monolithic megaton detector, but it allows the second Hyper-K detector to be placed in a different location, 300 km further from Tokai along the T2K beam, in South Korea. This would not affect the atmospheric neutrino and proton decay experiments, but would provide T2K with a greater handle on neutrino oscillations.

Even if Super-K is eventually superseded by Hyper-K, its location and enclosure should prove useful to future experiments; the pioneering KamLAND reactor neutrino experiment located its rather different detector in the original KamiokaNDE chamber, for example. Barring another catastrophe, the particle physics world should continue to see interesting results from Super-K for many years to come.