What are the causes and treatments of pimples or acne?

Pimples or acne are a combined result of several bodily changes that occur around puberty. During puberty, secretion of the hormone called androgen increases in both boys and girls. Androgen can also increase because of hormonal changes related to pregnancy or starting or stopping birth control pills. It normally happens around teenage and makes the sebaceous (oil) glands become more active. Sebaceous glands are on the hair follicles under the skin. In humans sebaceous glands exist throughout the body except the palms and soles. There is abundance of sebaceous glands on the face. These glands produce sebum, an oily substance which carries dead skin cells through the follicles to the surface of the skin. In normal circumstances sebum is produced in small amount and is discharged through a narrow pore on the skin. But if the quantity of sebum produced is high, it is not discharged as easily. It accumulates under the skin and the part near the pore turns black because of oxidation with the air. This part is generally referred to as blackhead. Blackheads spoil the looks, and it doesn't stop there. After a while bacteria develop in the sebum and that causes inflammation of the skin, worsening the pimple. After the sebum is removed, there remains a permanent dent on that part of the skin.

Formation of Acne

To some extent, genes are found to be responsible for pimples or acne. If one's parents had pimples, once stands greater chances of having pimples. However, upon noticing the first signs of pimple certain precautions can be taken to prevent its growth.

  • It is advisable to wash the face with warm water at regular intervals.
  • Using lotions and creams is not at all advisable as cosmetics that have oily content may clog pores.
  • Excessive chocolate consumption is suggested to aggravate pimples by some researchers. Although this research hasn't found all round support, but chocolate is anyway better avoided.
  • Milk and milk products are also found responsible for pimples.

If pimples or acne increase too much then a lotion containing a form of vitamin A called Retinol or an antibiotic like Tetracycline are advisable. Ultraviolet treatment may also be necessary after consulting a skin specialist.

Additional Reading:
Androgen (Wikipedia)
Sebaceous gland (Wikipedia)
Retinol (Wikipedia)
Tetracycline (Wikipedia)

Why does the ocean appear blue? Is it because of the sky's reflection?

Common sense would suggest that the ocean should appear green, because about two meters below the surface of the ocean the water is filled with organisms and plants containing chlorophyll (a green pigment) which provide about 70% of oxygen quota to the life on Earth. However, the British physicist Lord Rayleigh (who isolated Argon gas in the Earth's atmosphere in the year 1894) investigated this phenomenon and explained that the ocean appears blue because it reflects the color of the sky.

C. V. Raman
Years later in the year 1921, an Indian scientists C.V. Raman (photo, left) was returning via sea route from Britain after attending a physics related session. When he saw blue color of the ocean he remembered the Nobel Prize winner Lord Rayleigh's explanation about it. It then occurred to Raman that if the ocean was indeed reflecting the color of the sky then after filtering the blue color with polarizer we should be able to see the real color of the sea. Subsequently he carried out this experiment, but even after filtering the blue color with polarizer the ocean looked blue. The explanation Raman derived was: Like the sky, the ocean's molecules do not absorb blue light of the sun rays. Red, orange and yellow are absorbed by the water while the color blue is scattered. By scattering we mean the process by which radiation is absorbed and then reradiated by the material through which it passes. This is the same reason why the sky looks blue. For this explanation C.V. Raman was accorded Nobel Prize for physics in the year 1930.

The significance of this discovery was that it gave way to the new science of spectroscopy.

Additional reading:
C. V. Raman (Wikipedia)
Chlorophyll (Wikipedia)
Spectroscopy (Wikipedia)

What are the true primary colors, if not red, yellow and blue?

Primary colors are generally defined as 1) the colors that can not be made by combining any other colors, and 2) can be blended to make all the other colors. Almost all of us have learned in school that there are three primary colors - red, yellow and blue. If we revisit the definition of primary colors, we will see red and blue fail on both counts. One can make red by blending yellow with magenta, and blue is made by blending magenta with cyan. (See diagram on the left.) Moreover, a wide range of colors is inaccessible if we just start with red, yellow and blue.

The true primary colors are cyan, yellow and magenta. If you look at color printer cartridges, you will see that they come in these three colors. Color theorists had figured this out by the end of the 19th century, yet most school textbooks have got it wrong even today!

Why do eyes close when sneezing?

A sneeze arises to eject out bacteria, virus or some possibly allergic foreign substance. It's kind of an explosion that throws out the air from our lungs at maximum speed of 160 kilometers. All the muscles of chest, neck and face have to contract to create this explosion. These include the muscles attached to eyelids as well. That's the reason eyes can not be kept open while sneezing. This a reflex action, so however hard one tries one can't sneeze with eyes open.

Related post:

How do induction cooktops work? Are they cheaper than gas?

In an induction stove there is a copper coil under the ceramic cooking plate, whereas a particular type of inductive vessel is placed on the plate. When alternating current (AC) is passed through the coil, oscillating magnetic field is formed. As per physical law of induction this "induces" electric current. The current that passes into the metallic vessel heats up the vessel due to resistance in the metal, and the vessel in turn cooks up the food in it. (See, diagram below.)

Comparing this to a gas stove, the flame of a stove wastes certain amount of thermal energy in heating up the air along with the vessel. During tests the most efficient induction cooker took 2.58 minutes to boil a specific quantity of water, whereas the same quantity of water took 5.36 minutes to reach the boiling point on a gas stove. Thus, induction cooker may very well turn out to be a cost saver.

Why is the center of the Earth still hot?

4.6 billion years into its existence the lava at the core of the Earth is still not freezing. The internal heat of the Earth is due mainly to four sources. 1) About 10,000ยบ Celsius of heat generated at the time of Earth's formation is still not discharged in the space. 2) A few crore years after the Earth's formation a space object the size of Mars collided with Earth and the impact generated immense heat. Our moon is formed of debris resulted out of this massive collision. 3) Internal flow of liquids in the Earth generate heat out of friction with substances they come in contact with. 4) The core of the Earth is rich with radioactive substances like uranium, thorium and potassium-40 which generate heat while decaying.

On one hand the already cooled down 6 to 40 kilometers thick external crust blocks internal heat from coming out, and on the other hand the flows of liquids and decay of radioactive substances below the crust constantly generate heat. As a result the core heats up all the more. This situation is favorable to the life on Earth though. If the Earth went the same way of the now cold Mars then it would lose electrical flows at the core and in turn magnetic fields. Once the protective shield vanishes, Sun's intense radiation would kill the life on Earth.

Why do dogs run behind cars and bikes?

Dogs, like many predators, instinctually run after things that are moving away from them. This instinct is developed in them through evolution because in the past a dog's food was anything that ran away from it. It is partly about hunting and partly about defending their territory. All dogs possess to some extent an instinct to chase large rapidly moving objects. Some breeds of dogs are more likely than others to chase after cars because their chase instincts are so modified over time. For example, working breeds like retrievers have their hunting instincts diverted into fetching game for human hunters. Shepherds, bred for generations to herd cattle, are particularly prone to car-chasing as the large, swiftly moving cars generically resemble the creatures they were bred to chase.

It is advisable to not run when a dog barks at you. It would bark for some time and then lose interest and walk away.
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