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Black. The bear's fur seems white, but it is devoid of pigment, the hairs are hollow. Probably for this reason, it perfectly transmits solar radiation. Dark skin absorbs solar energy, which helps to survive in the cold climate of the Arctic.

In late pregnancy, a woman may develop a pathology called preeclampsia, which is characterized by an increase in blood pressure and the appearance of edema. This condition can be complicated and develop into eclampsia, which threatens the life of the mother and child. It can be caused by many reasons, among which there are immunological factors, namely the tolerance of the body to the father of the child, whose genes are present in the fetus and placenta. Several independent studies have supported the hypothesis that exposure of the female body to the sperm of the future father long before conception reduces the risk of developing preeclampsia. A significant reduction in risk is also given by oral sex already during pregnancy, and especially by swallowing semen after intercourse.

Detergents are substances that make things clean. Soap is one of the types of detergents. But when we say "soap", we mean a cleaning agent made from natural materials. And when we say "detergent", we mean a substance made from synthetic materials. Synthetic detergents are made by combining various chemicals in a complex manufacturing process. Petroleum products, fats, resins and other components are part of the complex composition of these substances. They are produced in chemical plants with special equipment.

Those components of detergents that have a real cleaning effect are called surfactants, abbreviated as surfactants. They can be made from a variety of raw materials, such as petroleum products, animal and vegetable fats.

The chemical processes involved in production are very complex. For example, animal fats can be processed with various chemicals: alcohol, liquid hydrogen, sulfuric acid, alkalis - to make only one type of surfactant. The surfactant should be mixed with other chemicals that help remove dirt more thoroughly and prevent it from settling back on things that are washed or laundered.

Special bleaches, dyes and foaming agents may also be added. Synthetic detergents have become so popular because they can lather in any type of water - soft or hard, cold or hot. In this case, there is no sediment that remains on the walls of the bath. Most of the products we use in dishwashing and laundry are synthetic detergents. Soap is basically a personal hygiene item.

There are about 50 varieties of peacocks in the world, but they all live on the tropical islands of the western Pacific and in northern Australia. The sizes of peacocks fluctuate between the sizes of a sparrow and a crow. Each type of peacock has a special "diamond" pattern. It is this bright color of plumage that makes these birds so unusual. But in fact, these magnificent creatures are relatives of the common crow.

The first Europeans to discover the peacock were the Dutch pioneers in the XNUMXth century. The birds looked so beautiful that the travelers called them birds of paradise (as they are called in English - "bird of paradise"). The famous colorful feathers are only found in male peacocks. Why they are needed is still unknown. Maybe to attract a female or distract the enemy from a nest with chicks.

Most peacocks build fragile, flat nests in the tops of trees. There they lay spotted eggs with streaks. Peacocks eat almost everything they can find, from fruits to snails and insects.

During the mating season, males show off their feathers in front of females. These usually wary birds are so addicted to such games that they let hunters in very close range. Locals shoot peacocks with blunt arrows so as not to damage the plumage.

From North America.

The symbols of the deserts of Arabia and Africa by origin are Americans.

Like horses and dogs, camels evolved on the steppes of America 20 million years ago. True, then they looked more like giraffes or gazelles than like the humpbacked pack giants that we know and love so well. Only 4 million years ago camels decided to cross Beringia - the isthmus that once connected Alaska with Eurasia.

Camels left North America during the last ice age and, unlike horses and dogs, never returned to their historical homeland.

No one knows why North American camels became extinct. Of course, climate change is to blame, first of all. More precisely, the disappearance of camels could be due to changes in the percentage of silicon in pasture grass. As the climate of the North American continent became cooler and drier, the silicon content of grasses tripled. Because of such super-hard food, even the longest-toothed herbivores wore out their incisors, and horses and camels, no longer able to chew food, gradually died of hunger.

There are also a number of indications that these already weakened individuals - the path to Asia for which was now closed forever due to the disappearance of Beringia 10 thousand years ago - were simply finished off by human hunters.

Doctors have been giving blood transfusions to patients since ancient times. There was a time when they even tried to transfuse blood from an animal to people who suffered from a large blood loss, but it always ended badly. Transfusion of even human blood often led to the death of the patient, so there was a time when laws forbade doctors to perform this procedure.

In the last decade of the 1868th century, the Austrian immunologist Karl Landsteiner (1943-XNUMX) discovered that the blood of different people can be divided into groups and that there are groups that are incompatible with one another. He found that sometimes when one person's whole blood is mixed in a test tube with the blood serum of another person (serum is the liquid part of the blood left after red blood cells and clotting factors have been removed from it), the red blood cells of the whole blood stick together.

If this happens during a transfusion, the clumped red blood cells will clog the blood vessels and stop blood flow, which can lead to the death of the patient. This, however, does not always happen: sometimes the mixing of blood does not lead to the formation of dangerous clusters of cells.

In 1900, Landsteiner published the results of his research, laying the foundation for modern transfusiology, the science of blood transfusion. According to modern concepts, there are 4 main groups of human blood: A, B, AB and 0.

Each person's blood belongs to only one of these groups. If the blood of two people belongs to the same group, it can be transfused from one to another without any risk. Moreover, group 0 can be transfused to people with other groups (A, B, and AB), and groups A and B can be transfused to group AB. But if you transfuse blood of group AB to people with blood types A or B, or transfuse the blood of people with groups A or B to each other, or transfuse a person who has blood type 0, the blood of any other group, then this will lead to aggregation of red blood cells.

We are still in it.

Geographers define the ice age as a stage in the geological history of the Earth, during which "ice caps" - glaciers - are present at its poles. Today's climate is an "interglacial". But this does not mean "between ice ages". The term is used to describe a stage within an ice age when, due to warming, the ice is receding.

"Our" interglacial began 10 years ago - during what is commonly considered the fourth ice age. When it ends, one can only guess: versions about the duration of the interglacial allow a gap from 000 to 12 years (without correction for human technogenic activity).

The reasons for these fluctuations are not entirely clear. Possible factors include both the position in which the land is located and the composition of the atmosphere, as well as a change in the Earth's orbit around the Sun. And possibly the Sun's own orbit inside the Galaxy.

During the so-called Little Ice Age, which began around 1500 and lasted 300 years, the average annual temperature in Northern Europe fell by one degree Celsius. The drop in temperature coincided with a period of extremely low solar activity, although the extent to which these two factors are related is still the subject of scientific discussion.

During the Little Ice Age, the Arctic ice sheet extended so far south that we know of six separate occasions when the Eskimos reached Scotland in their kayak boats, and the Orkney Islanders had to chase completely bewildered polar bears from their homes.

Recent research at Utrecht University links the Little Ice Age to the Black Death.

According to Dutch scientists, the catastrophic population decline in Europe during the epidemic led to the fact that the deserted farmlands were gradually overgrown with forests. And this, in turn, led to a significant decrease in carbon dioxide in the atmosphere and caused a decrease in average annual temperatures - a kind of "anti-greenhouse effect".

The 2010 Reykjavík city council election saw the participation of the "Best Party", founded shortly before by comedian Jon Gnarr. The party program contained many populist slogans and promises of all kinds of benefits, but it was immediately stipulated that the party would not fulfill these promises in the event of a victory. One of the points of the program was the statement that all other parties are secretly corrupt, so our party will be openly corrupt. As a result, "The Best Party" really became the first with a score of 34,7% of the vote, and Jon Gnarr took over as mayor of Reykjavik.

Did you know that bricks are the oldest building material? They began to be applied 5000 years ago. All bricks are made from clay. Clay is a common mineral, consisting of very small particles of rocks. Some types of clay are formed by the destruction of mountains under the influence of weather conditions. Clay is found everywhere on the surface of the earth, often at the bottom of lakes and rivers.

In its raw form, clay is very plastic and elastic. As it dries, it hardens and becomes very durable. When the clay is heated to very high temperatures (about 450 degrees Celsius), chemical changes occur, after which the clay will never become soft and plastic, even when wetted. This means that fired clay bricks will not soften or lose their shape when placed in a humid environment.

Bricks are fired at a temperature of 870 to 1200 degrees Celsius. At 535 degrees Celsius, the bricks turn red, which darkens with increasing temperature. Brick production has changed little since ancient times. The only difference is that most of the work these days is done by machines.

Clay is mined by excavators. After drying, it is crushed so that the particles become the same size. The clay is mixed with water to form a thick paste, which is forced out through a square-shaped outlet, like a huge tube of toothpaste. This extruded tape is automatically cut into pieces of the right size with knives or wire.

Soft bricks are dried in heated tunnels and sent to the kiln on a railway trolley. Each brick, on average, can withstand a load of up to 350 kilograms per square centimeter without collapsing.

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