Note, Table, and Flow-Chart Completion

No treatment on the market today has been proved to slow human aging. But one intervention, consumption of a low-calorie yet nutritionally balanced diet, works incredibly well in a broad range of animals, increasing longevity and prolonging good health. Those findings suggest that caloric restriction could delay aging and increase longevity in humans, too. But what if someone could create a pill that mimicked the physiological effects of eating less without actually forcing people to eat less, a caloric-restriction mimetic?

The best-studied candidate for a caloric-restriction mimetic, 2DG, works by interfering with the way cells process glucose. It has proved toxic at some doses in animals and so cannot be used in humans. But it has demonstrated that chemicals can replicate the effects of caloric restriction; the trick is finding the right one.

Cells use the glucose from food to generate ATP, the molecule that powers many activities in the body. By limiting food intake, caloric restriction minimizes the amount of glucose entering cells and decreases ATP generation. When 2DG is administered to animals that eat normally, glucose reaches cells in abundance but the drug prevents most of it from being processed and thus reduces ATP synthesis.

Researchers have proposed several explanations for why interruption of glucose processing and ATP production might retard aging. One possibility relates to the ATP-making machinery's emission of free radicals, which are thought to contribute to aging and to age-related diseases by damaging cells. Reduced operation of the machinery should limit their production and thereby constrain the damage.

Another hypothesis suggests that decreased processing of glucose could indicate to cells that food is scarce and induce them to shift into an anti-aging mode that emphasizes preservation of the organism over such luxuries as growth and reproduction.

A. The world's one and only rotating boat lift, The Falkirk Wheel, was opened in 2002 in Scotland. It was an ambitious Millennium Link project constructed to restore navigation across Scotland by bringing together the historic waterways of the Forth and Clyde and Union Canals.

B. The biggest challenge of the project is the fact that the Forth and Clyde Canal is situated 35 metres below the level of the Union Canal. Historically, the two canals were linked near Falkirk by a series of 11 locks. The link was cut when this was removed in 1933.

C. Many ideas and concepts were submitted for the project. A concept for the massive spinning steel boat lift that would become The Falkirk Wheel was eventually chosen as the winner. The structure's shape is said to have been influenced by man-made and natural elements, including a Celtic double-headed axe, a ship's massive propeller, whale ribcage, and fish spine.

D. The components of The Falkirk Wheel were constructed at Butterley Engineering's Steelworks in Derbyshire and assembled 400 km from Falkirk. The structure was then dismantled and brought to Falkirk in 35 lorries, before being bolted back together on the ground and raised into place in 5 big pieces by crane. To make the structure more robust, the steel components were bolted together rather than welded together.

E. The Falkirk Wheel has two sets of opposing axe-shaped arms, at about 25 metres apart to a fixed central spine.

F. Two water-filled gondolas, each diametrically opposed and having a capacity of 360,000 litres, are fitted between the ends of the arms. Whether or not they are hauling boats, these gondolas always weigh the same. Floating objects displace their own weight in water. As a result, when a boat enters a gondola, the volume of water exiting the gondola is equal to the weight of the boat. This maintains the Wheel's balance, allowing it to rotate through 180 degrees in 5.5 minutes while consuming relatively less energy.

G. Boats requiring lifting enter the canal basin at the level of the Forth and Clyde Canal, then the Wheel's lower gondola. Two hydraulic steel gates are raised to isolate the gondola from the canal basin's water. After that, the water between the gates is pumped out. A hydraulic clamp that stops the Wheel's arms from moving while docked is released, allowing the Wheel to turn. The central axle is then rotated by a 10-motor array in the central machine room. The axle links to the Wheel's outer arms, which begin rotating. A simple gearing arrangement keeps the gondolas upright as the wheel turns. Two 8-metre-wide cogs orbit a fixed inner cog of the same width, connected by two smaller cogs that go in the opposite direction as the outer cogs, ensuring that the gondolas are constantly level. The boat passes directly onto the aqueduct, 24 metres above the canal basin, when the gondola reaches the top.

H. A pair of locks provide the final 11 metres of elevation required to access the Union Canal. Because of the historically significant Antonine Wall, the Wheel could not be built to elevate boats over the entire 35-metre distance between the two canals. Boats pass through a tunnel beneath the wall, through the locks, and onto the Union Canal.

A. According to the latest figures, the majority of the world's population is now bilingual or multilingual. In the past, such children were considered to be at a disadvantage compared with their monolingual peers. Over the past few decades, however, technological advances have allowed researchers to look more deeply at how bilingualism interacts with and changes the cognitive and neurological systems.

B. Research shows that when a bilingual person uses one language, the other is active at the same time. Long before a word is finished, the brain's language system begins to guess what that word might be. For bilingual people, this activation is not limited to a single language. Some compelling evidence for this phenomenon, called language co-activation, comes from studying eye movements. A Russian-English bilingual asked to pick up a marker from a set of objects would look more at a stamp than someone who does not know Russian, because the Russian word for stamp, marka, sounds like marker.

C. Having to deal with this persistent linguistic competition can result in difficulties. Knowing more than one language can cause speakers to name pictures more slowly and can increase tip-of-the-tongue states. As a result, the constant juggling of two languages creates a need to control how much a person accesses a language at any given time. For this reason, bilingual people often perform better on tasks that require conflict management. In the classic Stroop Task, people see a word and are asked to name the colour of the word's font. Bilingual people often excel at tasks such as this, which tap into the ability to ignore competing perceptual information and focus on the relevant aspects of the input. Bilinguals are also better at switching between two tasks.

D. It also seems that the neurological roots of the bilingual advantage extend to brain areas more traditionally associated with sensory processing. When researchers play the same sound to monolingual and bilingual adolescents in the presence of background noise, the bilingual listeners' neural response is considerably larger, reflecting better encoding of the sound's fundamental frequency.

E. Such improvements in cognitive and sensory processing may help a bilingual person process information in the environment, and help explain why bilingual adults acquire a third language better than monolingual adults master a second language.

F. Research also indicates that bilingual experience may help keep cognitive mechanisms sharp by recruiting alternate brain networks to compensate for those that become damaged during aging. Older bilinguals enjoy improved memory relative to monolingual people. In a study of over 200 patients with Alzheimer's disease, bilingual patients reported initial symptoms an average of five years later than monolingual patients.

G. Furthermore, the benefits associated with bilingual experience seem to start very early. In one study, researchers taught seven-month-old babies that when they heard a tinkling sound, a puppet appeared on one side of a screen. Halfway through, the puppet began appearing on the opposite side. Only the bilingual babies were able to successfully learn the new rule.