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Showing posts with label Science and Nature. Show all posts
Showing posts with label Science and Nature. Show all posts

Sunday, 26 June 2016

The Mathematical Ability of Plants

PLANTS use a complex process called photosynthesis to extract energy from sunlight to create food. Studies on certain species have revealed that they perform yet another feat—they calculate the optimum rate at which to absorb that food overnight.

Consider: By day, plants convert atmospheric carbon dioxide into starch and sugars. During the night, many species consume the starch stored during the day, thus avoiding starvation and maintaining plant productivity, including growth. Moreover, they process the stored starch at just the right rate—not too quickly and not too slowly—so that they use about 95 percent of it by dawn, when they start making more.

The findings were based on experiments on a plant of the mustard family called Arabidopsis thaliana.Researchers found that this plant carefully rations its food reserves according to the length of the night, no matter whether 8, 12, or 16 hours remained until dawn. Evidently, the plant divides the amount of starch available by the length of time remaining until dawn, thus determining the optimal rate of consumption.

How do plants ascertain their starch reserves? How do they measure time? And what mechanism enables them to do math? Further research may shed light on these questions.

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The whales are back

Every year, beginning in July, female southern right whales (Eubalaena australis) arrive at the southern coast of Santa Catarina, Brazil. They come from as far as the subantarctic, thousands of miles away, to give birth and nurse their calves in shallow waters. For several months residents and tourists at the beaches or on the cliffs are thrilled to watch the whales—mothers and calves resting or frolicking in the water!

Giant Acrobatic Marine Creatures

A female can be 52 feet (16 m) long, about the size of an articulated bus, and weigh up to 80 tons! Its massive body is generally black, sometimes with white patches on the belly. The head is enormous, a quarter of the entire body length. The mouth is long and arched. This whale has no dorsal fin as do some other species. To swim forward, it flexes its broad and deeply notched tail up and down, instead of side to side as fish do. To change direction, it moves its flippers. This is similar to the way an airplane is steered.Curiously, despite their immense proportions, right whales have considerable flexibility, performing some amazing acrobatics. You can see them sailing, the tail sticking out of the water for long periods; lobtailing, raising the tail and slapping the water hard; and breaching, thrusting themselves out of the water and then falling back with a great splash that can be seen from far away.

Distinctive Physical Characteristics

On and around the head, the right whale has a series of whitish or yellowish callosities—roughened patches of skin covered by colonies of small crustaceans (cyamids) known as whale lice. “Each callosity pattern is unique,” explains Karina Groch, coordinator of the Brazilian Right Whale Project, “just as each person’s fingerprints are unique, enabling the identification of individual right whales. We take photos of whales’ callosity patterns when they visit our shores and keep these photos in a directory.”Biologists say that it is difficult to tell the right whales’ age when they die because this species of whale has no teeth. They estimate the whale’s life expectancy to be at least 65 years on average.

Curious Eating Habits

Right whales feed on tiny crustaceans. On each side of the whales’ upper jaw are filtering structures made up of hundreds of baleen plates that are fringed with fine hairs. As they swim, their open mouth allows water to filter through the baleen plates, capturing the tiny prey in the baleen hairs. By this means each whale can consume up to two tons of crustaceans a day.Southern right whales spend the summer (January/February) feeding in the Antarctic Ocean, building up blubber. This thick layer of fat provides excellent insulation when they are in cold waters and serves as food reserves when they migrate.

How Did They Get Their Name?

From the 18th century onward, whalers hunted these whales extensively in the Southern Hemisphere. They were considered the “right” whales to hunt. Why? Being slow swimmers, they were an easy catch, even for whalers in frail wooden boats that were equipped with only handheld harpoons. Besides, unlike other whales, right whales float when they are killed because of their extraordinary amount of blubber. Thus, whalers could easily drag them to the beach.In addition, blubber and baleen were important commodities at the time. Blubber was used in street oil lamps and as a lubricant. Baleen was fashioned into things such as corset stays, buggy whips, and umbrella ribs. In fact, baleen plates obtained from one whale alone would cover the expenses of an entire expedition!In the early 20th century, over-intensive hunting greatly reduced the right whale population, and eventually whaling was no longer commercially viable. In Brazil, the last whaling station was closed down in 1973. While there has been a slow recovery of some species, others remain critically endangered

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The Human Body’s Ability to Repair Wounds

AMONG the numerous mechanisms that make human life possible is the body’s ability to heal wounds and regenerate damaged tissue. The process begins as soon as an injury occurs.

Consider: The healing process is made possible by a cascade of complex cellular functions:
~>Platelets adhere to tissues around a wound, forming a blood clot and sealing damaged blood vessels.
~>Inflammation protects against infection and removes any “debris” caused by the injury.
~>Within days, the body begins to replace injured tissue, make the wound contract, and repair damaged blood vessels.
~>Finally, scar tissue remodels and strengthens the damaged area.

Inspired by blood clotting, researchers are developing plastics that can “heal” damage to themselves. Such regenerating materials are equipped with tiny parallel tubes containing two chemicals that “bleed” when any damage occurs. As the two chemicals mix, they form a gel that spreads across the damaged areas, closing cracks and holes. As the gel solidifies, it forms a tough substance that restores the material’s original strength. One researcher admits that this synthetic healing process currently under development is “reminiscent” of what already exists in nature.

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The Color-Changing Ability of the Cuttlefish

CUTTLEFISH can change their color and camouflage themselves, becoming almost invisible to the human eye.
According to one report, cuttlefish “are known to have a diverse range of body patterns and they can switch between them almost instantaneously.”

How do cuttlefish do it?
Consider: The cuttlefish changes color by using the chromatophore, a special kind of cell found under its skin. Chromatophores contain sacs that are full of colored pigment and that are surrounded by tiny muscles. When the cuttlefish needs to camouflage itself, its brain sends a signal to contract the muscles around the sacs. Then the sacs and the pigment within them expand, and the cuttlefish quickly changes its color and pattern. The cuttlefish may use this skill not only for camouflage but also to impress potential mates and perhaps communicate.
Engineers at the University of Bristol, England, built an artificial cuttlefish skin. They sandwiched disks of black rubber between small devices that function like cuttlefish muscles. When the researchers applied electricity to the skin, the devices flattened and expanded the black disks, darkening and changing the color of the artificial skin.Research on cuttlefish muscles—“the soft structures that nature is so good at making,” according to engineer Jonathan Rossiter—could lead to clothing that changes color in a fraction of a second. Rossiter says that people might wear cuttlefish-inspired clothes for camouflage—or simply for fashion.

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