Reading — 2026 Jan–Apr Recall Set 3

Olive oil is produced from the fruit of the olive tree, which is a member of the Oleaceae plant family. The trees require some cold weather during the year, but also tolerate hot, dry conditions, and do not like moisture when they are flowering. They actually produce better when subjected to these stressful conditions, and as a result, olive trees have traditionally been grown on land where little else will survive. Archaeologists today are divided over exactly where the first domestication of the olive occurred: some say it was in the area which is now Iran, Syria, Jordan and Egypt, while others contend it was in mainland Greece or on the island of Crete. The one thing that can be said with certainty is that cultivation began at least 6,000 years ago and spread slowly westward across the lands bordering on the Mediterranean Sea. Olive oil was used for a variety of purposes during these early times, including as a pharmacological ointment and in rituals for anointing royalty. The ancient Greeks believed the olive tree was a priceless gift from the goddess Athena and used its oil in sacred religious rituals. In fact, the Greek poet Homer called olive oil ‘liquid gold’, and during the 6th and 7th centuries BC, Greek law forbade the cutting down of olive trees and made it punishable by death. The ancient Middle Eastern ruler King David valued his groves of olive trees and his olive oil warehouses so much that he posted guards around the clock to protect them. Over the years, olive oil developed other uses. Its employment in cooking dates at least as far back as the 5th century BC, as described by the Greek philosopher Plato. Its use as an aid to beauty and health later became ingrained in many Mediterranean cultures. The Romans, for example, are said to have used generous amounts on their bodies to moisturise their skin after bathing. With the spread of the Roman Empire, olive oil became a major commodity, and its trade promoted commerce throughout the ancient world. It is generally believed that in the 1st–2nd centuries BC, olive trees were taken to North Africa and then to Spain, which was later to become the world’s largest producer of olive oil. Artefacts found at various Mediterranean archaeological sites include olive oil storage vessels with olive plant residue still in them. Historical evidence still in existence in the form of wall paintings and ancient manuscripts (including the works of the Roman naturalist and philosopher, Pliny the Elder) all record production techniques and the various uses of olive oil. Making olive oil in those early days was a laborious process accomplished without mechanisation. Processing or milling the fruit involved several distinct stages to extract the liquid. The olives were harvested from the trees by hand or by beating the fruit from the trees with long sticks. The olives were then rinsed and crushed to separate out the large seed found in the centre of each. The remaining seedless flesh was put in woven bags and pressed. Hot water was then poured over the bags to separate the oil from the solid bits of olive. The liquid produced in this process, consisting of oil and water, was drained into stone basins or tanks, where it was allowed to settle and separate. In cold weather, a bit of salt was added to speed up the process. As much oil as possible was drawn off the water, but the result was still not pure oil. Therefore, this impure mixture was allowed once more to settle in vats and then separated in order to refine the product. The waste water from the milling process, which is called amurca, is a bitter-tasting and foul-smelling liquid. In many ancient civilisations it was often simply discarded, causing serious pollution because of its acidity and high salt content. However, in the Roman period it was regarded as a very useful substance. When spread on surfaces, amurca forms a hard finish and therefore it was often applied to the floors of grain storage buildings where it hardened, keeping out water, mud and pests. When boiled down, amurca was applied to leather to soften it so that it was easier to shape into articles of clothing and shoes. It could also be eaten by farm animals and was, in fact, fed to livestock suffering from malnutrition. According to ancient texts, amurca was also utilised in moderate amounts by farmers as a fertiliser or as a pesticide, helping them to protect their crops from insects and even small rodents.

A For farmers, working out the optimal amount of seed, fertiliser, pesticide and water to scatter on a field can be a matter of luck, despite several harvests. Regular laboratory analyses of soil and plant samples from various sections of a field can help — but such expertise is costly, and often unavailable. However, a new and cheaper method of doing this analysis is now on offer. Precise prescriptions for growing crops can be obtained quickly, and less expensively, by calculating the amount of electromagnetic radiation reflected from agricultural land. The data is collected by orbiting satellites. B Examining the wavelength of radiation that is reflected can reveal, with surprising precision, the properties of the soil, the quality of crop being grown, and the levels in those crops of chlorophyll, various minerals, moisture and other indicators of their quality. If recent and forecast weather data is added, detailed maps can be produced indicating exactly how, where and when crops should be grown. The service usually costs less than US $15 per hectare for a handful of readings a year, and can increase yields by as much as 10%. C Such precision farming using satellite-based intelligence is a relatively new technique. Even so, it is catching on quickly. Five years ago, for example, a French cereal-growers' co-operative called Sevepi purchased a satellite and makes it available to its members in the form of maps of their fields, divided into three or four colour-coded zones per hectare. For each zone, the exact and best fertiliser formula is recommended. On top of this, if the amount of rain in the field has already grown quite high early in the season, and heavy showers are expected, an appropriate dose of growth regulator is recommended for each zone (as fragile stems break more easily in downpours). Then, farm vehicles equipped with global-positioning system locators automatically mix and apply the prescribed dose to each area. D France is the pioneer in this sort of surveillance. More farmland is analysed by satellite there than in any other country, according to Infoterra (a subsidiary of EADS Astrium), the firm that is France’s largest provider of such information, supplying data to companies such as Sevepi. Moreover, Henri Douche, head of Infoterra's agriculture sales in Toulouse, reckons the amount of monitored farmland will increase as weather patterns change and farmers can no longer rely on the past as a guide to the future. When confounded by the yield variations that these new weather patterns will bring, even farmers who are afraid of new technology will sign up, he says. E Inexpensive data on the productivity of land is advantageous to governments too. Areas where fertilisers and pesticides are being applied excessively can be pinpointed, enabling a reduction in environmental and land-use damage. Says Guy Lafond, an agronomist with Agriculture and Agri-Food Canada, a government agency, says the satellite data it purchases is proving useful for the study of fields with declining productivity in the province of Saskatchewan. Over-application of nitrate fertilisers (which are also a source of greenhouse gases) appears partly responsible. And according to RapidEye, a German satellite operator, some companies are also studying satellite data with a view to selling insurance policies to governments of famine-prone countries that might be threatened by crop failure. F In March, RapidEye began selling data that helps forecast harvests. "Too often, farmers limit productivity by managing fields wrongly," says Fredrick Jung-Rothenhäuser, head of product development at the firm's headquarters in Brandenburg an der Havel. "Our satellites are the first commercial satellites to include the Red-Edge band of the light spectrum, which is sensitive to changes in chlorophyll content. More research will be necessary to realise the full benefits of the Red-Edge band. However, this band can assist in monitoring vegetation health, improving species separation and also help in measuring protein and nitrogen content in biomass." The company's data, which comes from both Europe and the Americas, breaks field productivity down into patches just five metres square. G The advantages that satellite technology provides in terms of precision farming do not have to be restricted to rich countries. In Africa, where many areas have become badly depleted of nutrients, better fertiliser management would help reverse this situation. As a consequence, the charitable trust World Agroforestry Centre, in the city of Nairobi, in Kenya, has begun to build up a collection of radiation patterns derived from around 100,000 samples of African soils. The aim of this work is to help by understanding the potential of these soils to be more agriculturally productive. Once passed on to the International Centre for Tropical Agriculture, based in Colombia, South America, it is intended that the information be used to build a database called the 'Digital Soil Map'. When complete, this will provide farmers with free forecasts, developed with regularly updated satellite imagery, across farmland in the poorest countries in Africa. This is information which will almost certainly assist in improving crop yields. For a hunger-ravaged continent, that is good news indeed.

Academics are now working more with filmmakers who are impressed by the results of their research in computer-generated imagery (CGI). Every year the film academy in the USA celebrates the outstanding achievements of the year in a ceremony known as the Oscars. An increasingly important component of the ceremony is the presentation of the Scientific and Technical awards. In 2004 a notable event took place: the academic world met the cinematographic world when researchers from Stanford University in the USA were awarded an Oscar. These researchers, led by Steve Marschner, were from the field of Computer Graphics at Stanford. They were part of a growing cohort of computer scientists that has become fundamental to moviemaking. Films have shown that it is possible to use CGI to make actors look younger, older, weaker or stronger than they actually are in a surprisingly realistic manner. At least, it is possible if the altered actors are not filmed too closely. This is because the difficulty of recreating the textures of both skin and fabric means that the effect is less convincing when seen close up. The work of Marschner and his colleagues has greatly improved the accurate and realistic modeling of both skin and fabric. They recognized that one of the difficulties of creating lifelike characters in the computer world is that, in CGI, the characters’ skin is opaque (two-dimensional) whereas real skin is in fact translucent (three-dimensional), that is to say, it is semi-transparent. Marschner and his colleagues received the Oscar for their work in successfully producing a CGI model that simulates translucency; this is when light penetrates skin and then scatters below the skin’s surface before re-emerging. This is called subsurface scattering, and the mathematics for the model goes back many decades to the time when it was used in astrophysics. Because human skin is naturally translucent, it was necessary to be able to create this artificially in order to simulate the soft appearance of real skin. Previous CGI models, which assumed that skin was entirely opaque, resulted in characters with a plastic appearance. The scientists’ new model of CGI was so important in bringing digital characters to life that, within two years of their original research paper, all the major special-effects studios had incorporated it into their digital rendering systems. However, despite their award, the scientists, with admirable tenacity, continued their search for perfection, as they still did not feel that they had yet satisfactorily recreated the subtle ways light is reflected. To do this, they began to look in detail at the way skins and fabrics reflect light differently according to their make-up: the exact arrangement of fibers in fabric and the network of fibers in skin. Marschner and his team tried to do this by using computerized tomography, which is most familiar as a medical technique for examining people’s internal organs. Like classical radiology, it uses X-rays, but because the image is constructed inside a computer using exposures taken from many different positions, rather than a single exposure on photographic film, it can capture fine details that are invisible in classical radiography. Unfortunately, the scientists understood that at this point in time they could not use computerized tomography on skin, because a very high-intensity X-ray is needed to show the kind of detail they wanted and this would be very dangerous for human skin. They have, however, had some success with fabric. Using this new method of imaging, they are able to accurately record the three-dimensional structure of all the fibers in a number of small pieces of fabric. These same pieces of fabric, through the use of CGI, can then be patched together to form an entire garment inside a computer, in the same way that a small group of actors can be made to look like hundreds of people gathered together. A garment created through CGI is therefore made up of pieces of fabric whose internal structure has been pre-recorded. This means that the way light is reflected by the garment can be calculated far more realistically than if the scientists just made a computer model of what they thought the interior of the fabric looked like. Cinematography will benefit from this because, although it may take some years to be able to use computerized tomographic imaging of skin, for the moment the movement of a virtual cloak or the lifting of a computerized hat should look far more realistic. In the meantime, according to Marschner’s colleague Kavita Bala, the technology might have an application in online retailing. At the moment, people buying clothes over the internet have only a standard photograph to help them choose their purchases. It is hoped that if online shoppers can view items which have been presented through the use of computerized tomography graphics, they will have a much better understanding of what the material the item is made of is really like. Marschner is now working on the way light is scattered from individual hairs. He says, ‘I feel lucky to be working in this niche. I’m a visual person and to be able to spend my time scrutinizing the world around me, trying to understand why it looks the way it does, is very rewarding’.