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Why do Fingernails Grow Faster than Toenails?

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Dermatologists confirm that the rate of fingernail growth outstrips that of toenails, with the former lengthening anywhere from slightly faster to perhaps three times as fast. The American Academy of Dermatology puts the average rate of fingernail growth at about 0.1mm a day.

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The reason for the difference is uncertain but speculation is it is because of blood circulation which is better in the hands than in the feet. According to biopsy reports, the further down in the leg, the slower things are to heal, with an even slower cell turnover rate as you go further down to the toes.

Fingernail cells are formed in the matrix, under the cuticle, and are gradually extruded, dying, hardening and becoming mashed together as they are pushed out by the new cells. The root of the fingernail produces most of the volume of the nail and the nail bed beneath it. The bed contains the blood vessels, nerves and melanocyte cells responsible for skin colour. As the nail is produced by the root, it streams down along the nail bed, making it thicker. Nail growth is also affected by hormones, age, climate and time of year. Hair seems to grow a little faster in summer and the same is true for nails.

Sources: The Telegraph ( Kolkata, India)

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Why Scratching Brings Relief ?

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Oh, it brings such blessed relief and now scientists can tell you why   scratching an itch temporarily shuts off areas in the brain linked with unpleasant feelings and memories.

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“Our study shows for the first time how scratching may relieve itch,” Dr Gil Yosipovitch, a dermatologist at Wake Forest University Baptist Medical Center in Winston-Salem, North Carolina, said in a statement.

Prior studies have shown that pain, including vigorous scratching, inhibit the need to itch. Yosipovitch and colleagues looked at what goes on in the brain when a person is scratched.

He and colleagues used a technique known as functional magnetic resonance imaging to see which areas of the brain are active during scratching. They scratched 13 healthy people with a soft brush on the lower leg on and off in 30-second intervals for a total of five minutes.

Scratching reduced activity in the anterior cingulate cortex and the posterior cingulate cortex — areas linked with pain aversion and memory. And the more intensely a person was scratched, the less activity they found in these areas of the brain.

“It’s possible that scratching may suppress the emotional components of itch and bring about relief,” Yosipovitch said. But they also found why one scratch often begets another.

Scratching increased activity in the secondary somatosensory cortex, a pain center, and in the prefrontal cortex, which is linked with compulsive behaviour.

“This could explain the compulsion to continue scratching,” Yosipovitch said. The researchers noted that the study is limited because people were not scratching in response to an actual itch.

But they said understanding what goes on in the brain may lend clues about how to treat people tormented by chronic itch, including people with eczema and many kidney dialysis patients. The study, which appears online in the Journal of Investigative Dermatology, was paid for by the National Institutes of Health.

Sources: The Times Of India

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Why Can’t We Write With Both Hands Simultaneously?

The problem lies not only in writing two different words together with both of our hands, but writing anything simultaneously at all.

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This is due to the fact that most people are adept at using only one hand. In fact, the majority of people are right-handed, with only four per cent using the left hand.

The human body is not fully symmetrical. There is a little asymmetry between the left and the right part of the body. Usually, the right side of the body is slightly heavier than the left side. Our brain is also divided into left and right parts. Even the functions of the parts are somewhat different. Normally the left half of the brain dominates over the right. In such a case, nerves originating from the brain cross over at the level of the neck and go to the right side of the body. Such persons are right-handed. But in a few cases, where the right half of the brain dominates, the nerves coming out of the brain pass onto the left parts of the body. Such people are left-handed.

Therefore, a person is efficient while using only one of his hands. Ambidexterity is an exception.

The human brain also has different centres for controlling different cultural activities like speaking, writing and so on. The hypothetical writing centre can only regulate one activity

Sources:The Telegraph (Kolkata, India)

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Why Does Hair Keep Growing?

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It is really intriguing that hair, although composed of dead cells, keep growing. The secret of its growth lies in the hidden part of hair that remains under the skin.

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Hair originates from a ring of dividing cells which later die out and contribute to its growth. At the base of the skin layer dermis? there are two distinct layers of skin, inner dermis and outer epidermis?  the se-ed of growth is sown as a cluster of dividing cells in a follicle (small sac-shaped cavity).

These cells divide continuously depending on the nutrients and oxygen supplied by the skin tissue and blood vessels that surround the dividing cells. In the follicle, nascent cells move upward through the centre. The innermost cells die and harden into hair while the rest also die, giving rise to a double-layered hair sheath. Every dead cell adds to the length of the hair.

Just before it sprouts through the skin, hair is bathed in oil from the sebaceous gland which secretes oily matter. Hair growth may be affected by factors like nutrition, temperature, hormonal imbalance and diseases. The popular notion that frequent haircuts help hair growth is, of course, wrong.

Sources: The Telegraph (Kolkata, India)

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Why Do Gas Bubbles Form Beneath Champagne?

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Gas bubbles that form in a liquid, including the vapour bubbles that form as water boils, require tiny flaws (lack of homogeneity) to seed them. A baby bubble then adds other pockets of gas and grows, and once it has expanded to a certain size, it tears off and starts to rise.

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In case of champagne the necessary flaws are found on the surface of the glass that contains it. Carbon dioxide bubbles form at preferred spots and rise up in a line from it. Those that originate at the bottom of a champagne glass are obvious because they rise to the middle. Others may form at the sides and slide up unnoticed because of the steep shape of the glass.

The bubble inception process is called nucleation, and the formation of the tiny pressure depression that lets it happen is called cavitation.

Surface tension (a tension of the surface film of a liquid, tending to minimise its surface area) on the surface of the bubble for-ms a barrier to bubble growth. It is very ha-rd to cavitate a pure fluid because it needs a little void to start the bubble. In other words, it takes a bubble to make a bubble.

To boil a liquid without an explosive effusion of it, chemists use a rough-surfaced object, a boiling stone, to encourage cavitation.

Sources: The Telegraph (Kolkata, India)

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