雅思阅读 基础段

Numeration

New Understanding of Giraffes in the Wild

Fishbourne Roman Palace

Fishbourne Roman Palace is in the village of Fishbourne in West Sussex, England. This large palace was built in the 1st century AD, around thirty years after the Roman conquest of Britain, on the site of Roman army grain stores that had been established after the invasion during the reign of the Roman Emperor Claudius in 43 AD. The rectangular palace was built around formal gardens, the northern half of which has been reconstructed. There were extensive alterations in the 2nd and 3rd centuries AD, with many of the original black-and-white mosaic floors being overlaid with more sophisticated coloured ones, including a perfectly preserved mosaic of a dolphin in the north wing. More alterations were in progress when the palace burnt down in around 270 AD, after which it was abandoned.

Local people had long believed that a Roman palace once existed in the area. However, it was not until 1960 that the archaeologist Barry Cunliffe of Oxford University first systematically excavated the site, after workmen had accidentally uncovered a wall while they were laying a water main. The Roman villa excavated by Cunliffe's team was so grand that it became known as Fishbourne Roman Palace, and a museum was erected to preserve some of the remains. This is administered by the Sussex Archaeological Society.

In its day, the completed palace would have comprised four large wings with colonnaded fronts. The north and east wings consisted of suites of private rooms built around courtyards, with a monumental entrance in the middle of the east wing. In the north-east corner there was an assembly hall. The west wing contained state rooms, a large ceremonial reception room and a gallery. The south wing contained the owner's private apartments. The palace included as many as fifty mosaic floors, under-floor central heating and a bathhouse. In size, Fishbourne Palace would have been approximately equivalent to some of the great Roman palaces of Italy, and was by far the largest known Roman residence north of the European Alps, at about 500 feet (150 m) square. A team of volunteers and professional archaeologists is involved in an ongoing archaeological excavation on the site of nearby, possibly military, buildings.

The first buildings to be erected on the site were constructed in the early part of the conquest in 43 AD. Later, two timber buildings were constructed, one with clay-and-mortar floors and plaster walls, which appears to have been a house of some comfort. These buildings were demolished in the 60s AD and replaced by a substantial stone house, which included colonnades and a bath suite. It has been suggested that the palace itself, incorporating the previous house in its south-east corner, was constructed around 73–75 AD. However, Dr Miles Russell of Bournemouth University re-interpreted the ground plan and the collection of objects found, and has suggested that, given the extremely close parallels with the imperial palace of Domitian in Rome, its construction may more plausibly date to after 92 AD.

With regard to who lived in Fishbourne Palace, there are a number of theories. For example, one proposed by Professor Cunliffe is that, in its early phase, the palace was the residence of Tiberius Claudius Cogidubnus, a local chieftain who supported the Romans and who may have been installed as king of a number of territories following the first stage of the conquest. Cogidubnus is known from a reference to his loyalty in Agricola, a work by the Roman writer Tacitus, and from an inscription commemorating a temple dedicated to the gods Neptune and Minerva found in the nearby city of Chichester. Another theory is that it was built for Sallustius Lucullus, a Roman governor of Britain in the late 1st century, who may have been the son of the British prince Adminius. Two inscriptions recording the presence of Lucullus have been found in Chichester, and the redating by Miles Russell suggests that, if the palace was designed for Lucullus, then it may have been in use for only a few years, as the Roman historian Suetonius records that Lucullus was executed by the Emperor Domitian in or shortly after 93 AD.

Additional theories suggest that either Verica, a British king of the Roman Empire in the years preceding the Claudian invasion, was the owner of the palace, or Tiberius Claudius Catuarus, following the recent discovery of a gold ring belonging to him. The palace outlasted the original owner, whoever he was, and was extensively re-planned early in the 2nd century AD and subdivided into a series of smaller apartments. Further redevelopment was begun in the late 3rd century AD, but these alterations were incomplete when the north wing was destroyed in a fire in around 270 AD. The damage was too great to repair, and the palace was abandoned and later dismantled.

A modern museum has been built by the Sussex Archaeological Society, incorporating most of the visible remains, including one wing of the palace. The gardens have been replanted using authentic plants from the Roman period.

The Development of Plastics

The first plastics were developed as a substitute for natural rubber. Chemically, rubber is a polymer—a compound containing large molecules that are formed by the bonding of many smaller, simpler units, repeated over and over again. The same bonding principle—polymerization—is the basis of the creation of a huge range of plastics by the chemical industry.

The first plastic was developed as a result of a competition in the USA. In the 1860s, $10,000 was offered to anybody who could replace ivory—supplies of which were declining—with something equally good as a material for making billiard balls. The prize was won by John Wesley Hyatt, with a material called celluloid. Celluloid was made by dissolving cellulose, a carbohydrate obtained from plants, in a solution of camphor dissolved in ethanol. This new material rapidly found other applications in the manufacture of everyday products such as knife handles and detachable collars and cuffs. But perhaps the best-known celluloid product was photographic film, without which the film industry could never have taken off at the end of the 19th century.

Celluloid can be repeatedly softened and reshaped by heat, and is known as a thermoplastic. In 1907, Leo Baekeland (1863–1944), a Belgian chemist working in the USA, invented a different kind of plastic by causing phenol and formaldehyde to react together. Baekeland called it Bakelite, and it was the first of the thermosets—plastics that can be cast and moulded while hot, but cannot be softened by heat and reshaped once they have set. Bakelite was a good insulator, and was resistant to water and acid. With these properties it was soon being used in the manufacture of electrical switches as well as a variety of domestic items.

As the century went on, the range of newly developed plastics increased. Chemists began looking for other small molecules that could be strung together to make polymers. In the 1930s, chemists in Britain discovered that the gas ethylene would polymerize under heat and pressure to form a thermoplastic they called polythene. Polypropylene followed in the 1950s. Both are used to make bottles, pipes and plastic bags. A small change in the starting material—replacing a hydrogen atom in ethylene with a chlorine atom—produced rigid PVC (polyvinyl chloride), a fireproof plastic suitable for drains and gutters. By adding certain chemicals, a soft form of PVC can be produced, suitable as a substitute for rubber in items such as waterproof clothing. A closely related plastic is Teflon or PTFE (polytetrafluoroethylene). It produces very little friction, making it ideal for products such as non-stick frying pans.

Polystyrene, a hard, clear material like glass, was developed during the 1930s in Germany, and its applications included food containers and toys. Expanded polystyrene is rigid and is widely used in packaging and insulation. Polyurethane, developed in the same country, was commonly produced as a foam, which was very useful in the production of insulating materials.

In the 1930s, the first of the man-made fibres was created—nylon. Its inventor was a chemist called Wallace Carothers (1896–1937), who worked for the Du Pont company in the USA. He found that under the right conditions two particular chemicals would form a polymer that could be pumped out through holes and then stretched to form long glossy threads that could be woven like silk. Its first use was to make parachutes for the US armed forces in World War II. In the postwar years, it completely replaced silk in the manufacture of stockings.

Many other synthetic fibres joined nylon, including Orlon, Acrilan, and Terylene. Today most garments are made of a blend of natural fibres, such as cotton and wool, and man-made fibres that make fabrics easier to look after.

Despite its enormous usefulness, plastic has its drawbacks. In fact, one of its great strengths—its indestructibility—is its greatest disadvantage. Beaches all over the world, even on the remotest island, are littered with plastic bottles that nothing can destroy. Nor is it very easy to recycle plastics, as different types of plastic are often found in the same items and call for different treatments.

Plastics can be made biodegradable by incorporating into their structure a material such as starch, which is attacked by bacteria and causes the plastic to fall apart. Other materials can be incorporated that gradually decay in sunlight—although bottles made of such materials have to be stored in the dark, to ensure they do not disintegrate before they have been used.

The History of the Pencil

The history of the pencil starts with a violent thunderstorm. When some particularly ferocious weather struck the Lake District in North West England in the sixteenth century, locals in the village of Borrowdale discovered a large uprooted tree. Underneath the tree lay an unknown black substance which we now know as graphite, was slightly shiny and smooth to the touch. And it left a black smear on the hands of all who touched it.

Initially, the local farmers used the newly discovered material as a handy way to identify their sheep. However, others quickly realised the potential for using this intriguing substance to write on paper. When it was untreated the material was very soft, which meant that it was messy to handle. To make it fit for use with paper, people enclosed a thin core of the substance in stiff sheep hides or rope. At this time chemistry was still in its infancy. People searched for a word to describe this increasingly useful substance and came up with plumbago which, in Latin, means acts or writes like lead. Later the name was changed to graphite. But because words have remarkable staying power, we still call graphite the lead of a pencil even though it is now known that there is no trace of real lead in graphite.

Graphite has a very high melting point at around 3,500 degrees Celsius. This made it invaluable to the British army and navy as a secret ingredient in the manufacture of cannon balls. The Royal Ordnance, or weaponry section of the British armed forces, used graphite as a lining inside the moulds for cannon balls, which, as a result, the British could turn out faster and more cheaply than their European rivals. In addition to its value to the armed forces, the government quickly realised the commercial potential of the graphite at Borrowdale, and assumed control of all the mines there during the sixteenth century. Armed guards accompanied the precious graphite all the way down to the metal foundries by the naval shipyards in the south of England. The graphite was so valuable that the locals, who called it wad, started to steal it. As a deterrent, an act of Parliament in 1752 made this offence punishable by time in prison.

The Italians originally invented the wooden casing to hold a thin rod of plumbago firmly in place for ease of writing. Italian craftsmen hollowed out two small sections of cedar wood, into one of which they laid the lead. They then glued the other section over the top and left the two halves to set. When dry, the whole apparatus formed what today we know as a pencil. The Germans took this technique and developed it further by applying mass-production techniques to pencils. At the same time Nicolas-Jacques Conté, a French officer in Napoleon Bonaparte's army during the late 1700s, developed a method of mixing powdered graphite and clay together for firing in a kiln. Adding more clay to the mixture helped make the pencil harder, sharper, and more precise in its mark. More graphite helped make a pencil mark that was softer, thicker and darker.

The varying quality of pencil leads eventually gave rise to a system for categorizing the fineness of the pencil mark. Pencil manufacturers all over the world still use this so-called HB grading system today. The H stands for the Hardness of the pencil while the B stands for its Blackness. An HB pencil is a standard pencil and a variety of letters and numbers are used to designate different types of lead.

Significant seams of graphite exist in parts of China, which now produces most of the world's pencils. Interestingly, the Borrowdale mine in the Lake District remains the only significant source of graphite in its near-pure form in the world. Nowadays the highest grade of graphite at Borrowdale is totally exhausted, although other grades can still be found, and England's pencil industry continues to thrive in the nearby town of Keswick.

The pencil has turned out to be a remarkably resilient and valuable tool whose use has survived well into our high-tech times, as a well-known story shows. It is sometimes said that the American space programme spent millions of dollars to invent a pen capable of writing in the zero gravity of space. The Russians, by contrast, simply equipped their astronauts with good old-fashioned pencils that never let them down. It should be pointed out though, that the popular myth about Americans overlooking the practical advantages of pencils in zero gravity is merely fiction. In actual fact, both American and Russian astronauts were equipped with pencils in their respective countries' first space flights. A private company later developed pens for writing in zero gravity. In fact, astronauts of every nation now use pens. But no matter—pencils remain in use in every classroom, every planning, building and drawing office, and in every art studio in the world. And there is nothing to suggest that we are likely to invent anything better than graphite to use in our pencils.

The Early History of Olive Oil

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.

European Transport Systems 1990-2010

Urban Regeneration: an award-winning redevelopment project in Berlin

A Just over a kilometer south of Berlin's Potsdamer Platz, near the left bank of the Landwehr Canal, an extensive, triangular-shaped area of waste ground once separated the neighbourhoods of Kreuzberg to the east and Schöneberg to the west. Known as Gleisdreieck, meaning 'triangle of rails', it was formed by the intersection of different railway lines built in the mid-nineteenth century that entered Berlin from the south. Tracks, sheds and warehouses belonging to three old railway stations — Dresdner Bahnhof (1875-1882), Potsdamer Bahnhof (1838-1944) and Anhalter Bahnhof (1839-1952) — are situated on a raised area some twenty hectares in size, at a height of four metres above the surrounding ground level.

B As the railway infrastructure gradually ceased to be used, the whole area of Gleisdreieck became increasingly run down and abandoned, to the point of being used as a rubbish tip after 1945. Meanwhile, vegetation took over, turning it into a surprising, natural haven in the middle of built-up areas. The closeness of the wall which divided the city of Berlin between 1961 and 1990 also contributed to the fact that Gleisdreieck was for decades clearly identified as no-man's-land. Only a station of the same name in Berlin's underground railway system testified to its existence. Shortly before the fall of the Berlin Wall, however, the German Museum of Technology was established there, attracting large numbers of visitors and giving visibility to the site. More importantly, the unification of the formerly divided city gave the zone more centrality, at which point it became imperative to identify a purpose for it.

C After 2006, the State of Berlin put forward the proposal of converting Gleisdreieck into a large urban park that would integrate the different urban zones which converged there. The decades-long isolation of the site, which had formerly presented a problem, now represented an opportunity for joining the southern area of Potsdamer Platz with Kreuzberg and Schöneberg. The creation of the park would trigger one of the biggest urban expansions inside Berlin, all within a framework of multiple uses and social characteristics. It was necessary to stimulate the development of sixteen new hectares of local amenities that would be capable of integrating different generations and social groups in a sustainable way, and in harmony with nature. Following intense discussion with local proprietors and residents, the need to reconcile these goals with the conservation of railway heritage also emerged.

D Once the area had been subjected to a process of undergrowth clearance and decontamination, it was then organized around a combination of existing and added elements. The project as a whole was planned around a large central meadow, intersected from east to west by a concrete footpath, and from north to south by a pair of railway lines. Once a month, a train slowly travels along these lines from its parking shed to the German Museum of Technology. The concrete footpath, which is a continuation of one of the main Kreuzberg boulevards, starts in the east, bridges the four-metre difference in ground level by means of a stairway, and suddenly ends in the west on reaching the underground lines.

E North of the meadow, there is a large concrete slab with rounded edges. Being south-facing, this functions as a big sunny terrace, full of benches complete with footrests. In the south, the meadow overlooks Yorckstrasse, an underpass crossed by more than fifteen former railway bridges. To the east of the meadow there is quite a dense forest of pre-existing maples, oaks and birches, as well as newly planted trees of the same species. In this area, a couple of large metal frames each hold two swings. The edges of the park are finished with a collection of distinctive, functional spaces, for example a nursery, sports fields, concave surfaces for skateboards, stages for dancing, community gardens, or simply areas covered in gravel obtained from the site itself.

F Although initially the regeneration of Gleisdreieck Park was the subject of disagreement between those who were in favour of safeguarding the railway heritage and those who wanted to regenerate the adjacent neighbourhoods, it was opened to the public in September 2011. The heart of Berlin now has a new green lung, in which the atmosphere of various small, very different corners fits neatly into a large-scale, wide-ranging and robust general order. This has been possible precisely because the intervention was not limited to conserving industrial remains in order to promote railway history. And as a reminder of the six decades of human absence, during which nature took over, the park has been able to conserve to some extent the spirit of the non-place that preceded it.

Multi-tasking and the Brain

A Do you think you're a master of multi-tasking? Think again. Unless you are one of the three percent of super-taskers in the population, research shows that your brain isn't capable of paying close attention to more than one complex task at a time. Researchers who study attention say that effective multi-tasking is beyond most of us. Psychiatrist Edward M Hallowell even describes multi-tasking as 'a mythical activity in which people believe they can perform two or more tasks simultaneously as effectively as they can perform one'.

B It is true that you can check your email while eating your lunch, or listen to music while walking. But innate activities like walking, chewing, and breathing do not require you to pay attention, whereas activities such as reading, tapping out a text message, or driving a car do require attention. Why is paying attention to two things at once difficult? 'The brain can perform simultaneous tasks, but attention has capacity limitations,' says Associate Professor Paul E Dux, a cognitive neuroscientist at the University of Queensland in Australia. When you do only one thing at a time, you're better at that task than when you're doing multiple things concurrently. Take the classic multi-tasking scenario of talking on a mobile phone while driving - an ill-advised activity that many people believe they have mastered. When David Strayer, Professor of Psychology at the University of Utah in the US, and his team observed 56,000 drivers as they approached an intersection, the majority of drivers who were talking on their phone failed to stop in accordance with traffic laws. And it did not matter if the driver was using a handheld or hands-free device. Even with both eyes on the road and both hands on the wheel, drivers' performance was impaired. Strayer's research shows that performance deteriorates drastically when attention is split between tasks: more mistakes are made and it takes longer to complete each activity.

C The prefrontal cortex is the brain region responsible for choosing what to pay attention to, and for coordinating inputs from other brain areas. By scanning the prefrontal cortex of people while they multi-tasked, scientists at the French Institute of Health and Medical Research in Paris (INSERM) found that when people focused on a single thing, the right and left sides of the prefrontal cortex work together. But when people attempt to perform two things at once, the sides work independently. Neuroscientist Etienne Koechlin says his study demonstrates that while the brain can switch back and forth between two tasks, we might be in great trouble when we try to juggle more than two tasks, simply because we have only two frontal lobes.

D To the question of whether there is a difference between the sexes, Koechlin's imaging studies uncovered no differences in the ability to switch between tasks in the prefrontal cortices of men or women. But other researchers studying real life scenarios such as finding lost keys, believe there might be some truth to the claim that women are superior multi-taskers. Women have a much better strategy for finding the keys, whereas men tend to jump to it and be far less organised and thorough. 'It's as if they don't stop to reflect and plan for a moment,' says Professor Keith Laws from the University of Hertfordshire in England. But while the ability to develop strategies for coping with the numerous tasks in everyday life could give women an advantage, 'nobody can juggle two, never mind three, "complex" tasks at the same time.'

E However, David Strayer's research uncovered that some rare people possess extraordinary multi-tasking ability. These so-called 'super-taskers' exhibit different patterns of brain activity when multi-tasking compared to ordinary people: they show less activity in the prefrontal cortex during multi-tasking, suggesting their brains are functioning with a high level of efficiency. Strayer thinks that pilots of high-performance aircraft, high-end chefs who can cook several meals at the same time to perfection, and elite doctors in hospital emergency rooms might all be more likely to be super-taskers. 'All other things being equal, we suspect that super-taskers will rise to a top position in any occupation that places a high demand on juggling various tasks that demand attention at the same time.'

F The ability to multi-task probably comes down to the DNA you inherit from your parents to a large extent, says Strayer. 'You are either born with the neural structure that allows you to overcome the usual multi-tasking challenges, or you aren't. Super-taskers' brains are doing something we can't do.' All in all, these findings may have very real consequences on our lives.

How do plants talk to each other?

A In 1983, plant scientists Jack Schultz and Ian Baldwin reported that the leaves of young maple trees increased their defense systems when exposed to maples that had been damaged by plant-eating (herbivorous) insects. The injured trees, they suggested, were alerting neighbors to the presence of a predator by releasing chemical signals into the air. But the plant research community did not accept this. The results were difficult to replicate, critics pointed out. Many also questioned how it could be evolutionarily stable if it benefited neighboring plants but not the plant releasing the signal. By the late 1980s, most ecologists felt that Schultz and Baldwin's ideas had been discredited.

B A decade later, however, a number of more carefully designed experiments began to yield convincing indications to the contrary. In 2000, evolutionary ecologist Richard Karban showed that wild tobacco plants became resistant to herbivores when grown in close proximity to sagebrush plants whose leaves had been damaged by cutting. This change appeared to be in response to chemicals — known as volatile organic compounds or VOCs - released by the sagebrush plants. Other researchers soon reported similar VOC-induced defense responses in several other plants, including lima bean, broad bean, barley, and corn. And in 2006, Karban showed that VOCs released by damaged sagebrush induce herbivore resistance in plants growing at distances of up to 60 cm, well within the range of sagebrush neighbors in nature.

C But the question still remains: 'Why should a plant waste valuable resources on a function which has no obvious advantage for it?' One hypothesis is that external communication channels are merely an extension of within-plant signaling. In sagebrush, lima bean, and poplar, VOCs released from damaged parts of a plant induce resistance in intact sections of the same plant, suggesting that each individual plant uses the signals to coordinate its own physiological responses to protect itself. Karban agrees, saying: 'The interplant signaling we see may be a result of plants co-opting that process.' Alternatively, VOC-based signaling between plants may have been favored because it enhances the 'extended fitness' of the sender by aiding related plants of the same species: a strategy known as kin selection.

D Over the past few years, a team led by Ariel Novoplansky of Ben-Gurion University of the Negev in Israel seems to have found proof that distress signals can be passed through the plants' roots. They planted garden pea plants in rows and subjected the first in each row to conditions similar to those experienced in a drought. They then evaluated the response by measuring the microscopic holes on leaves, known as pores, which react when there is a shortage of water. After fifteen minutes, the stressed plant was seen to be closing its pores, followed by all of its neighbors, one by one. Importantly, in a control setup where root contact between neighboring plants was blocked, pores stayed open.

E Monica Gagliano of the University of Western Australia believes that plants may even use sounds to alert their neighbors. In one study, she demonstrated that chili plants growing next to fennel plants developed more quickly than seedlings grown with other chili plants. Gagliano and her colleagues suspect the chili plants were compensating for the presence of the fennel, which is known to release chemicals that inhibit the growth of other plants. Remarkably, however, when plant communication pathways — airborne volatiles, root contact, and common fungal networks — were blocked, the results begged for an alternative explanation. 'We think this other channel of communication might be acoustic,' says Gagliano. But behavioral ecologist Carel ten Cate of the University of Leiden in the Netherlands points out that taking advantage of such benefits would require sensory mechanisms yet to be described in plants. Despite widespread skepticism, Gagliano has received some encouragement. Richard Karban, for example, is cautiously enthusiastic. 'Whether or not the explanation she favors is the right one,' he says, 'I think that she's gotten results that, as a field, we need to come to grips with.'

F Researchers believe that knowledge of this phenomenon could eventually be applied to agriculture, and lead to the cultivation of hardier crops. But all agree that there is still much work to be done. 'Applying our limited knowledge [of plant-communication mechanisms] to agriculture is a big jump,' says Johnson, 'but it is definitely on the horizon.' Nevertheless, one message has emerged loud and clear from those studying this new realm of botanical interaction: despite not possessing eyes, ears, or a nervous system, plants are anything but uncommunicative. 'When I started my PhD (in the late 1980s), all this stuff was considered very weird,' recalls Ariel Novoplansky. 'Today, there is no doubt. We now recognise that plants are capable of some very sophisticated exchanges of information with other plants. This idea is not strange anymore.'

A new look for Talbot Park

Talbot Park, a housing project in Auckland, New Zealand, was once described as a ghetto, troubled by high rates of crime and vandalism. However, it has just been rebuilt at a cost of $48 m and the project reflects some new thinking about urban design.

A The new Talbot Park is immediately eye-catching because the buildings look quite different to other state-housing projects in Auckland. 'There is no reason why state housing should look cheap in my view,' says architect Neil Cotton, one of the design team. 'In fact, I was anticipating a backlash by those who objected to the quality of what is provided with government money.' The tidy brick and wood apartments and townhouses would not look out of place in some of the city's most affluent suburbs, and this is a central theme of the Talbot Park philosophy.

B Talbot Park is a triangle of government-owned land, which in the early 1960s was developed for state housing built around a linear garden that ran through the middle. Initially, there was a strong sense of neighbourliness. Former residents recall how the garden played a big part in their childhoods — a place where kids came together to play softball, cricket and bullrush. 'We had respect for our neighbours and addressed them by title — Mr and Mrs so-and-so,' recalls Georgie Thompson, who grew up there in the 1960s.

C Exactly what went wrong with Talbot Park is unclear. The community began to change in the late 1970s as more immigrants moved in. The new arrivals didn't always integrate with the community and a 'them and us' mentality developed. In the process, standards dropped and the neighbourhood began to look shabbier. The buildings themselves were also deteriorating and becoming run-down, petty crime was on the rise and the garden was considered unsafe. In 2002, Housing New Zealand decided the properties needed upgrading. The question was, how to avoid repeating the mistakes of the past?

D One controversial aspect of the upgrade is that the new development has actually made the density of housing in Talbot Park greater, putting 52 more homes on the same site. Doing this required a fresh approach that can be summed up as 'mix and match'. The first priority was to mix up the housing by employing a variety of plans by different architects: some of the accommodation is free-standing houses, some semi-detached, some low-level, multi-apartment blocks. By doing this, the development avoids the uniform appearance of so many state-housing projects, which residents complain denies them any sense of individual identity. The next goal was to prevent overspending by using efficient designs to maximise the sense of space from minimum room sizes. There was also a no-frills, industrial approach to kitchens, bathrooms and flooring, to optimise durability and ensure the project did not go over budget. Architecturally, the buildings are relatively conservative: fairly plain houses standing in a small garden. There's a slight reflection of the traditional Pacific beach house (a fale) but it's not over-played. 'It seems to us that low-cost housing is about getting as much amenity as you can for the money,' says architect Michael Thompson. Another key aspect of the 'mix and match' approach is openness: one that not only lets residents see what is going on but also lets them know they are seen. The plan ensures there are no cul-de-sacs or properties hidden from view, that the gardens are not enclosed by trees and that most boundary fences are see-through — a community contained but without walls.

E The population today is cosmopolitan: 50% Pacific Islanders, 20% Maori, 15% Asian, 10% New Zealand European and the rest composed of immigrants from Russia, Ukraine and Iran. 'It was important that the buildings were sufficiently flexible to cater for the needs of people from a wide variety of cultural backgrounds,' explains designer James Lundy.

F Despite the quality of the buildings, however, there should be no doubt that Talbot Park and its surrounding suburb of Tamaki are low socio-economic areas. Of the 5,000 houses there, 55% are state houses, 28% privately owned (compared to about 65% nationally) and 17% private rental. The area has a high density of households with incomes in the $5,000 to $15,000 range and very few with an income over $70,000. That's in sharp contrast to the more affluent suburbs in Auckland.

G Another important part of the new development is what Housing New Zealand calls 'intensive tenancy management'. Opponents of the project call it social control. 'The focus is on frequent inspections and setting clear guidelines and boundaries regarding the sort of behaviour we expect from tenants,' says Graham Bodman, Housing New Zealand's regional manager. The result is a code of sometimes strict rules: no loud parties after 10 pm; no washing hung over balcony rails; and a requirement to mow lawns and keep the property tidy. The Tenancy Manager walks the site every day, knows everyone by name and deals with problems quickly. 'It's all based on the intensification,' says project manager Stuart Bracey. 'We acknowledge that if you are going to ask people to live in these quite tightly-packed communities, you have to actually help them to get to know each other by organising morning teas and street barbecues.' So far it seems to be working and many involved in the project believe Talbot Park represents the way forward for state housing.

A new look for Talbot Park

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Multi-tasking and the brain

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A Do you think you're a master of multi-tasking? Think again. Unless you are one of the three percent of super-taskers in the population, research shows that your brain isn't capable of paying close attention to more than one complex task at a time. Researchers who study attention say that effective multi-tasking is beyond most of us. Psychiatrist Edward M Hallowell even describes multi-tasking as 'a mythical activity in which people believe they can perform two or more tasks simultaneously as effectively as they can perform one'.

B It is true that you can check your email while eating your lunch, or listen to music while walking. But innate activities like walking, chewing, and breathing do not require you to pay attention, whereas activities such as reading, tapping out a text message, or driving a car do require attention. Why is paying attention to two things at once difficult? 'The brain can perform simultaneous tasks, but attention has capacity limitations,' says Associate Professor Paul E Dux, a cognitive neuroscientist at the University of Queensland in Australia. When you do only one thing at a time, you're better at that task than when you're doing multiple things concurrently.

Take the classic multi-tasking scenario of talking on a mobile phone while driving — an ill-advised activity that many people believe they have mastered. When David Strayer, Professor of Psychology at the University of Utah in the US, and his team observed 56,000 drivers as they approached an intersection, the majority of drivers who were talking on their phone failed to stop in accordance with traffic laws. And it did not matter if the driver was using a handheld or hands-free device. Even with both eyes on the road and both hands on the wheel, drivers' performance was impaired. Strayer's research shows that performance deteriorates drastically when attention is split between tasks: more mistakes are made and it takes longer to complete each activity.

C The prefrontal cortex is the brain region responsible for choosing what to pay attention to, and for coordinating inputs from other brain areas. By scanning the prefrontal cortex of people while they multi-tasked, scientists at the French Institute of Health and Medical Research in Paris (INSERM) found that when people focused on a single thing, the right and left sides of the prefrontal cortex work together. But when people attempt to perform two things at once, the sides work independently. Neuroscientist Etienne Koechlin says his study demonstrates that while the brain can switch back and forth between two tasks, we might be in great trouble when we try to juggle more than two tasks, simply because we have only two frontal lobes.

D To the question of whether there is a difference between the sexes, Koechlin's imaging studies uncovered no differences in the ability to switch between tasks in the prefrontal cortices of men or women. But other researchers studying real life scenarios such as finding lost keys, believe there might be some truth to the claim that women are superior multi-taskers. Women have a much better strategy for finding the keys, whereas men tend to jump to it and be far less organised and thorough. 'It's as if they don't stop to reflect and plan for a moment,' says Professor Keith Laws from the University of Hertfordshire in England. But while the ability to develop strategies for coping with the numerous tasks in everyday life could give women an advantage, 'nobody can juggle two, never mind three, "complex" tasks at the same time.'

E However, David Strayer's research uncovered that some rare people possess extraordinary multi-tasking ability. These so-called 'super-taskers' exhibit different patterns of brain activity when multi-tasking compared to ordinary people: they show less activity in the prefrontal cortex during multi-tasking, suggesting their brains are functioning with a high level of efficiency. Strayer thinks that pilots of high-performance aircraft, high-end chefs who can cook several meals at the same time to perfection, and elite doctors in hospital emergency rooms might all be more likely to be super-taskers. 'All other things being equal, we suspect that super-taskers will rise to a top position in any occupation that places a high demand on juggling various tasks that demand attention at the same time.'

F The ability to multi-task probably comes down to the DNA you inherit from your parents to a large extent, says Strayer. 'You are either born with the neural structure that allows you to overcome the usual multi-tasking challenges, or you aren't. Super-taskers' brains are doing something we can't do.' All in all, these findings may have very real consequences on our lives.

How do plants talk to each other?

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Research shows that plants communicate and interact with each other in surprisingly subtle ways.

A In 1983, plant scientists Jack Schultz and Ian Baldwin reported that the leaves of young maple trees increased their defense systems when exposed to maples that had been damaged by plant-eating (herbivorous) insects. The injured trees, they suggested, were alerting neighbors to the presence of a predator by releasing chemical signals into the air. But the plant research community did not accept this. The results were difficult to replicate, critics pointed out. Many also questioned how it could be evolutionarily stable if it benefited neighboring plants but not the plant releasing the signal. By the late 1980s, most ecologists felt that Schultz and Baldwin's ideas had been discredited.

B A decade later, however, a number of more carefully designed experiments began to yield convincing indications to the contrary. In 2000, evolutionary ecologist Richard Karban showed that wild tobacco plants became resistant to herbivores when grown in close proximity to sagebrush plants whose leaves had been damaged by cutting. This change appeared to be in response to chemicals — known as volatile organic compounds or VOCs - released by the sagebrush plants. Other researchers soon reported similar VOC-induced defense responses in several other plants, including lima bean, broad bean, barley, and corn. And in 2006, Karban showed that VOCs released by damaged sagebrush induce herbivore resistance in plants growing at distances of up to 60 cm, well within the range of sagebrush neighbors in nature.

C But the question still remains: 'Why should a plant waste valuable resources on a function which has no obvious advantage for it?' One hypothesis is that external communication channels are merely an extension of within-plant signaling. In sagebrush, lima bean, and poplar, VOCs released from damaged parts of a plant induce resistance in intact sections of the same plant, suggesting that each individual plant uses the signals to coordinate its own physiological responses to protect itself. Karban agrees, saying: 'The interplant signaling we see may be a result of plants co-opting that process.' Alternatively, VOC-based signaling between plants may have been favored because it enhances the 'extended fitness' of the sender by aiding related plants of the same species: a strategy known as kin selection.

D Over the past few years, a team led by Ariel Novoplansky of Ben-Gurion University of the Negev in Israel seems to have found proof that distress signals can be passed through the plants' roots. They planted garden pea plants in rows and subjected the first in each row to conditions similar to those experienced in a drought. They then evaluated the response by measuring the microscopic holes on leaves, known as pores, which react when there is a shortage of water. After fifteen minutes, the stressed plant was seen to be closing its pores, followed by all of its neighbors, one by one. Importantly, in a control setup where root contact between neighboring plants was blocked, pores stayed open. Meanwhile, David Johnson's team at the University of Aberdeen in Scotland have been studying the labyrinths of hair-like fungi that occur around the roots of most plants. These fungi are involved in an important two-way relationship: in exchange for sugars, they provide plants with much-needed phosphorus and nitrogen. Research in which broad bean plants were infested with aphids — small herbivorous insects — revealed that these networks also served as a channel for warning neighboring plants of the infestation.

E Monica Gagliano of the University of Western Australia believes that plants may even use sounds to alert their neighbors. In one study, she demonstrated that chili plants growing next to fennel plants developed more quickly than seedlings grown with other chili plants. Gagliano and her colleagues suspect the chili plants were compensating for the presence of the fennel, which is known to release chemicals that inhibit the growth of other plants. Remarkably, however, when plant communication pathways — airborne volatiles, root contact, and common fungal networks — were blocked, the results begged for an alternative explanation. 'We think this other channel of communication might be acoustic,' says Gagliano. But behavioral ecologist Carel ten Cate of the University of Leiden in the Netherlands points out that taking advantage of such benefits would require sensory mechanisms yet to be described in plants. Despite widespread skepticism, Gagliano has received some encouragement. Richard Karban, for example, is cautiously enthusiastic. 'Whether or not the explanation she favors is the right one,' he says, 'I think that she's gotten results that, as a field, we need to come to grips with.'

F Researchers believe that knowledge of this phenomenon could eventually be applied to agriculture, and lead to the cultivation of hardier crops. But all agree that there is still much work to be done. 'Applying our limited knowledge [of plant-communication mechanisms] to agriculture is a big jump,' says Johnson, 'but it is definitely on the horizon.' Nevertheless, one message has emerged loud and clear from those studying this new realm of botanical interaction: despite not possessing eyes, ears, or a nervous system, plants are anything but uncommunicative. 'When I started my PhD (in the late 1980s), all this stuff was considered very weird,' recalls Ariel Novoplansky. 'Today, there is no doubt. We now recognise that plants are capable of some very sophisticated exchanges of information with other plants. This idea is not strange anymore.'

The return of the black-footed ferret

The rise, fall, and rise of one of North America's rarest mammals

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A The black-footed ferret (Mustela nigripes) is a small carnivorous mammal, similar in length to a domestic cat, and is the only ferret species native to North America. For at least 100,000 years they lived in an area that extended almost uninterrupted from southern Canada to northern Mexico. But numbers fell dramatically throughout the 19th and 20th centuries, to such an extent that the black-footed ferret was declared 'possibly extinct'. Then, almost miraculously, it returned from the dead.

B Within the genus Mustela, the ferret belongs to the subgenus Putorius, of which there are only three extant species: the European polecat; the Siberian polecat; and the black-footed ferret. The European polecat lives in open forests and meadows, and is thought to be the ancestor of the domestic ferret. The Siberian polecat looks more similar to the black-footed ferret, and leads a similar life on open grasslands and semi-desert regions across Russia, China and Siberia.

C Ferrets probably evolved in Europe between three and four million years ago, and dispersed into North America across an ice-age land bridge at least two million years ago. They then advanced south-eastward to the Great Plains through ice-free passageways. The black-footed ferret's history in North America is inextricably linked to the creature which became almost its sole prey — the prairie dog. These small rodents are a type of ground squirrel which live in networks of underground tunnels, known as burrows. The black-footed ferret's short legs and long, slim body make it superbly adapted for life in the burrow systems of its prey.

D Spending virtually all their time underground, black-footed ferrets have always been elusive. Ferrets are never mentioned in accounts of the early explorers or pioneers who crossed the Great Plains by wagon train during the early to mid-1800s. They were, however, occasionally listed in records kept by fur companies in the upper Missouri River basin during that period. Black-footed ferrets were not officially recognized by scientists until 1851, when a description and drawing of one featured in a book by the renowned naturalist John James Audubon and Reverend John Bachman. For over two decades, no other specimens were seen, and scientists even began to question their existence. Then, in 1874, a Dr Elliott Coues issued a request for specimens through the popular magazine The American Sportsman, and was soon rewarded. With these he was able to add to Audubon's description, and confirm the existence of the black-footed ferret.

E In the decades that followed, European settlement across North America changed the landscape dramatically, with vast areas being transformed into crop and grazing land. As agriculture and ranching expanded, the black-footed ferret's main prey, the prairie dog, became a target for extermination, and was eventually eradicated from 98% of its original range. The result was devastating for black-footed ferret populations throughout the continent. Even today, the prairie dog is still trapped and poisoned, because ranchers believe that it competes with livestock for grass — a notion that belies recent research showing that prairie dogs and cattle feed on different plants.

F As late as the 1950s, black-footed ferrets were still thought to occur in low densities, throughout most of their historic range. However, by the 1960s, the only known population was a small colony in south-western South Dakota. In 1967, the US Fish and Wildlife Service classified the black-footed ferret as an endangered species, and in 1974 the South Dakota colony disappeared. Finally, in January 1979, the last ferret in a captive-breeding programme died — making the black-footed ferret the first mammal to be declared extinct in the Northern Hemisphere in the 20th century.

G But that was not the end of the story. In 1981, a farm dog called Shep carried an odd-looking creature to its owner's ranch house in Meeteetse, Wyoming. The rancher put the carcass in his fridge and alerted state officials. The dog had found a black-footed ferret — which led to efforts again being made to save the species. An intensive search in the region led to the discovery of a 130-strong population. This wild colony thrived for a while, but disaster struck again and the number of animals was drastically reduced by the disease distemper — probably contracted from domestic dogs. In 1985, in a final bid to save the species, the remaining 18 individuals in the colony were trapped for a new captive-breeding programme. This project was successful, and there are now more than 2,000 black-footed ferrets in captivity across the US and Canada.

H A reintroduction programme began in 1991. Before they can be reintroduced into their natural habitat, captive ferrets have to learn to hunt and escape from predators. They are first held in pens on the prairie, where they are fed prairie dog meat. Once the ferrets associate these animals with food, keepers unleash live prey into the pens, and they soon realise that they must hunt or go hungry. Then, to get the ferrets used to living underground, they have to be tempted into the holes with food.

I Reintroduction programmes are now underway across central USA, but there is one location that is key. The Janos area on the US-Mexico border is the obvious place to reactivate the continent's wild black-footed ferret population, being one of the most important remaining grassland ecosystems in the Americas, and home to an abundance of prairie dogs. At the last report, the future of the black-footed ferret finally looks promising.

GREYING POPULATION STAYS IN THE PINK

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