SHARKS vs HUMAN BEINGS

To my knowledge sharks will attack human only if there is any underwater noises or any attraction from human like jewellery or if there are many person taking their bath in underwater. So generally it will attack only if there is any noise or it can also attack if there is sudden waves arriving in seawater. Human normally creates these waves and this will be erratic in nature. Sharks generally attack during daytime and particularly when the sea temperatures are between 17 degree and 20 degrees centigrade. They will be normally some 250 feet from the shore. The most vigorous and dangerous sharks, which attack human, are the tiger and the blue and grey nurse sharks. The more powerful one is the white shark, which is extremely dangerous.

FROG’S BREATHING UNDER WATER

Frog is an amphibian i.e.. it can live both in land and in water. Everybody have some doubt in how they breathe under water. Let me clear this doubt for you. Frog has lungs as every human being but it doesn’t have ribs for expanding its chest which in turn helps in breathing through lungs. On land the air is inhaled only through frog’s nostrils which have valves in them by pulsation of the floor of the mouth. The air is inhaled and exhaled only by the throat and body muscles to the lungs. It always keeps its mouth shut tightly so the pulsation of the throat is about is 120-140 per minute. In water the frog is inhaled only through their skin. And even in land it is helping out in sometime. the frog’s skin should not be dry as it dies so the skin contains glands which secrete a clear mucus or slime whose function is to keep the skin moist and supple. The frog is a cold-blooded reptile. So it can change its temperature depending on its surrounding. In winter they hibernate under water, where the temperature of its body falls, thereby the body functions become reduced and breathing is carried out on entirely through skin.

WITH ITS SMALL BODY MASS, HOW DOES A MONARCH BUTTERFLY OBTAIN ENOUGH ENERGY TO MIGRATE 1800 MILES?

The energy is gathered from nectar, and the butterflies that make the trip, those born in the early fall, are able to convert nectar into fat. Those born in September know to tank up on nectar and their abdomens get really large. Unlike the other generations, these monarchs, he explained, have a little area of fatty tissue where the sugar of the nectar is converted into fat. They can live off this cushion in winter and need only water to rehydrate their bodies. Monarchs born in September or late august live seven or eight months, sometimes nine months too. Their children, grandchildren and great-grandchildren live just a month. By the time you get to the great great grandchildren it puts us back to September again. The butterflies also feed while migrating

WHY DO THE SUN AND MOON APPEAR MANY TIMES LARGER AT THE HORIZON?

 
The angular diameter of the sun and moon is about half a degree each. The celestial objects are seen with two eyes. When we observe the horizon, the terrestrial surface with all its objects, such as trees, houses, roads or ground give us a perspective view, i.e., farther the objects smaller they appear, as they subtend smaller and smaller angles at the retina. Through this long distance perspective, which some time extends to several kilometers, our vision is able to realize a long perceptual distance. At the end of this perspective we locate the celestial objects and realize a particular size. On the other hand, when we view these objects in the sky, the most important perspective is absent and consequently the two eyes are left with their own power to discern a distance. This binocular distance limit in the absence of the perspective has been found to be about 500 feet, which vary slightly from person to person. This can be checked by the absence of parallax shifts of objects beyond the distance when we view with alternate eyes. Therefore the sun and moon are located at a distance of about 500 feet must appear much smaller than a similar half degree object at a considerably long perceptual distance realized by the sense of vision with the help of perspective. In order to illustrate this phenomenon, we place a larger ball at a distance from the eye and a much smaller one just covers the angular dimension of the larger ball. Now both the balls subtend the same angle at the eye, but to our binocular vision the larger ball at that distance appears decidedly larger and it is physically larger. Through a telescope or a camera, the sun and moon appear of the same sizes either at the horizon or over the high sky. This view also applies to star constellations at the horizon and at the high sky. Monocular vision by one-eyed people has no illusion of this nature, because they have no perceptual depth.

WHY DON’T WE HAVE HAIR ON OUR PALMS?

In humans hair is present in the skin of nearly every part of the body excepting the palms of hands, the soles of the feet, the flexor surface of the digits. The structural components of the skin alone decide the generation of the appendages of the skin. Structurally the skin has two layers: the epidermis and dermis. Among these two layers, the epidermis has a high capacity for regeneration after damage. It continually replaces the outer dead cells and also generates the appendages of the skin, like hairs, nails, sweat and sebaceous glands. In the two parts of the hair, namely the root and shaft, the root is the structure which emerges first during development and is called the hair follicle. It is set in between of the epidermis and the superficial part of the dermis. Each hair follicle commences on the surface of the skin with a funnel shaped opening. From this opening the follicle passes inwards in an oblique or curved direction. At the deep end of each hair follicle there is a small conical vascular eminence called papilla, which is continuous with the dermal layer of the skin. The capillaries of the papilla provide nutrients to the hair. When any one of the layers of epidermis and dermis gets abnormal development it affects the formation of the hair follicle and also becomes an unfit layer to support the hair. For example, in the skin of palm and soles the stratum cornium of the keratinization of epidermis and reticular layer of dermis are comparatively thicker than in the skin of other parts of our body. Such a thick keratinization zone will not allow the formation of hair follicles and the thick dermis is not the ideal structure to support the germinal matrix of the hair follicles. That is why hairs do not grow on our palm of the hands and the soles of the feet.

HOW FAST IS THE EARTH MOVING THROUGH SPACE?

The earth is speeding like a top and like a merry-go-round horse on a carousel that is itself riding on a larger carousel, and the whole amusement park is moving through space. The earth rotates on its axis at about 460 metres per second at the equator. The speed of a trip around the sun is about 30km per second. Meanwhile, the solar system is in a more-or-less circular orbit around the centre of the galaxy at an average velocity of about 220 kilometres a second, according to Facts on File Dictionary of Astronomy, and the galaxy is moving at about 19.4 kilometres a second, toward a point in the constellation Hercules called the solar apex. Some authorities believe that there is also a general drift by the Milky Way and some neighbouring upper clusters towards the southern cross at a speed of more than a million miles an hour.

ICEBERGS

 
In those days Icebergs formed of fresh water that breaks of from various glaciers. These are formed in polar regions where you can find a huge snowfall lasting for more than many centuries. These icebergs doesn’t melt and these are compressed onto ice. It is formed from the tide water glaciers. The snow becomes compressed and it looks to be firm and transformed into a dense ice. But now-a-days these icebergs are melting because of global warming. This is not going to be a good sign as it increases the sea level which will ultimately lead to demolition of earth.

HOW DO CFCs DAMAGE THE OZONE LAYER?

Most of us don’t think about how our everyday activities might influence the global environment. An example is our use of chlorofluorocarbons or CFCs. These compounds which are useful as propellants in aerosol sprays, refrigerants, coolants, cleaning agents, insulants and plastic foam are the main eaters of ozone present in the ozonosphere. Ozonosphere is the general stratum of the upper atmosphere in which there is an appreciable ozone concentration and in which ozone plays an important part in the radiative balance of the atmosphere. It lies roughly between 10 and 50 kilometers, with maximum ozone concentration at about 20 to 25 kilometers. Ozone, O3, a blue gas is unstable allotropic form of oxygen. It is scarce, even in the astratosphere where it is most concentrated. But each molecule counts. Highly unstable, an ozone molecule readily splits up when hit by ultraviolet radiation. The energy of the life-damaging UV rays is thus converted into harmless heat and never reaches the earth. The breakup leaves a free oxygen atom (O) and an oxygen molecule (O2), the stuff we breathe. The O and O2, in an ongoing cycle, recombine to form new ozone molecules. The chlorofluorocarbons released by us are stable and can live up to 100 years. They are non-toxic and harmless to life. But when they drift slowly upward to reach the stratosphere by convection, they are struck by the high energy short wavelength radiations such as ultra violet rays and this initiates a ozone clearing process. When a CFC molecule is exposed to strong UV radiation in the stratosphere, it is broken apart. This release a chlorine atom, which attacks an ozone molecule, pulls away one of the three oxygen atoms and forms a chlorine monoxide molecule thus destroying the ozone molecule. The destructive process continues further. Free oxygen atoms freeing the chlorine atom to restart the cycle pull the oxygen atoms from the new chlorine monoxide molecule away; thus progressively more ozone molecules are decomposed. It has been estimated that one chlorine atom can eat up to 100000 molecules of ozone. A severe depletion in the ozone layer will result in an increase in the case of skin cancer, eye cataract and suppression of the immune system in humans and other species. Food crops sensitive to UV rays could also be affected. In 1984 a hole in the ozone layer was discovered over Antarctica and more recently a similar hole was discovered which extends over the Arctic, Scandinavia and North America.

WHY SHOULD WE SIT AT A DISTANCE WHILE WATCHING THE TELEVISION?

In simple terms, the eye consists of a cornea, eye lens and retina. The space between the cornea and the eye lens is filled with an aqueous humour and that between the lens and retina is filled with a vitreous humour. Ciliary muscles hold the eye lens in its place and also change the shape of the lens along with the help of the fluids. If one sits too close to the television or cinema screen, the eye lens has to do more frequent focusing for viewing. Light rays from a near portion of the picture diverge and so the lens is curved more to focus on them. Simultaneously, the lens has to collect the light from more distant parts of the picture. This causes strain on the eye, and if practiced for long, can permanently damage the eye. In addition, for optimum resolution of the picture and to reduce the level of radiation from the TV screen, we are advised to sit at a distance while watching the programs. In fact, the limit of resolution of the human eye is 1mm at a distance of about 3m. If one watches a TV sitting close to it one can see the picture elements, which make up the picture. To see a clear sharp picture without eye strain, one must sit at an optimum distance so that the individual grains merge to form a complete picture. In a typical case, the main field of vision of the eye is defined by the vertical and horizontal viewing of 30-40 degrees; beyond which the vision is poor. Therefore, for comfortable viewing, a viewing angle of 10-15 degrees at the eye is optimum. The width-to-height ratio of the TV screen is kept as 4:3 because of the binocular vision due to the pair of eyes in the horizontal plane and the range of movement of both the eyeballs being less restricted in the horizontal plane as compared to that in the vertical plane. Hence, the best viewing distance for watching TV is 4-8 times the height of the screen. For 51-cm TV, the minimum viewing distance should be 2.5 m. This minimum distance reduces eye fatigue by avoiding rapid movement of the eyeballs. Also the light that falls on the eyeball comes directly out of the TV screen. Hence the intensity of the harmful radiations coming out of TV screen is strong near it and gradually falls with the distance from the screen. So, to reduce exposure to these radiations, it is better to sit a bit far away. To reduce the strain on the eye, there must be some light in the hall. And this should be placed preferably above or on the sides of the TV to avoid any glare from the screen.

DANDRUFF

Dandruff is a condition of excessive scaliness of the scalp. There are two varieties-dry and greasy. In the dry variety, the scales are fine, thin, white or grayish, and dry or slightly greasy. Such type of hair lacks lusture. People with this type of hair will have mild to moderate itching. The scales will fall freely on the shoulders. This dandruff will be more common in winter than in summer. It signifies exaggeration of normal exfoliation of the horny layer of the epidermis. It usually affects people with dry integument and scalp. Such people are rather reluctant to use oil, on their scalp. In the greasy variety both the scalp and the integument are oily. It diffuses all over the scalp. Later the condition also extends to other hairy regions. It may extend typically to the eyebrows, eyelids, beard and other regions. The basic defect in this case is over production and/or change in composition of the sebaceous secretion. Dandruff is common at puberty and it occurs due to endocrine disorders, familial predisposition, unbalanced diet and constipation. Effective treatments for these conditions are prescribed, in siddha medicine, based on commonly available plant products

WHAT IS DRY EYE SYNDROME?

our eyes are lubricated by tears that are produced by glands around the eye.  There are two types of tears: moisturising tears and reflex tears. Moisturising tears are produced continuously, while reflex tears are produced in response to irritation or emotion. Dry eye syndrome is a condition in which production of moisturising tears is dramatically reduced, making the eyes feel scratchy and look red. When the eyes become irritated, some people experience reflex tearing, which is why tearing  can also be a symptom of dry eye syndrome. In addition, people with dry eyes sometimes find they can no longer comfortably wear contact lenses. There are many possible causes of dry eyes. The most common cause is age, because production of moisturizing tears decreases as people grow older. In women, hormonal changes- especially those associated with pregnancy or menopause-can result in dry eyes. Environmental irritants may also play a role. The treatment is lubrication.

HOW DO FRUITS RIPEN?

Ripening of fruits is associated with the process of senescence or aging in plants. It involves change in colour, texture, flavour, sugar content and acidity, and is influenced by the ripening hormone ethylene. As ripening begins there is a climacteric increase in respiration, which is followed by increased ethylene production. It triggers a series of biochemical changes such as lateral growth, loosening of cell walls resulting in more intercellular spaces, conversion of starch and organic acids into sugars, hydrolysis of stored materials, softening by enzymatic changes of pectin substances, decrease in chlorophyll content with corresponding increase in anthocyanin pigments and emission of characteristic volatile oils. It is well known that ethylene production is increased more than 100-fold during climate rise. Colour changes occur due to synthesis of carotenoids and phenolic compounds like anthocyanins. Changes in texture occur by limited degradation of cell walls followed by an increase in poly-galaturonase and pectin-esterase activity. In banana and apple, the enzyme phosphorylase and in mangoes, amylase, break the starch into glucose and sucrose leading to their sweet taste. Volatile compounds such as ethyl-2-methyl butrate elicit a sweet smell. He adds, acidity of fruits is due to the presence of malic acid, citric acid, and malic acid and tartaric acid. Ripening is a pre-requisite for the development of embryos after fertilization and for better dispersal of seeds for survival.

DO SHEEP SWIM? IF SO, HOW DO THEY LEARN?

Yes, sheep do swim, said Edward spevak, assistant curator of mammals at the Bronx Zoo. “It’s basically instinctive, a life-saving device,” he said. They don’t go swimming every day, but in case of flooding, or falling into a river, in essence they know how to swim. Sheep have never been known as big swimmers, and mose of the habitat where they evolved does not have a lot of water resources, but swimming is part of their repertoire of skills, he said. First of all, like many animals, they float, spevak explained, “Then, in struggling to keep the head above water and to keep breathing, the method they use is basically fast walking, which constitutes a kind of dog paddle,” he said. Other large mammals are swimmers, too. Spevak said. Cattle can swim when herded across a river, as Western movie fans know. Deer can swim, as well, “The moose, the largest deer in the world, actually feeds in water and is very good swimmer” Spevak said.

IS IT TRUE THAT A RED FLAG AGITATES A BULL?

It is generally believed that anything red makes a bull angry and causes it to attack. Therefore, the bullfighter has to have a bright red cape and use a red cloth. The truth is that if the bullfighter had any other coloured cloth he would be able to accomplish the same reaction from the bull. Bulls are colour blind. Many experiments were conducted where they used white cloth and got the bulls to behave in the same way as with the red cloth. The reason is the movement of the cap and not the colour of the cloth brings about the reaction in the bull. Anything waved in front of a bull would excite it.

HOW DO ANIMALS SEE IN THE DARK?

Photoreception is activation of a biological process by light. Most organisms including man respond to light. Some animals react to light waves not perceived by man. Vertebrates have two types of photosensitive cells, rods and cones, so called because of their shape. The rods, which are long and fat, contain large amounts of visual pigment and they mediate vision under dim illumination. The cone cells, which are relatively small, mediate daylight vision and colour sensation. The retinas of animals active both day and night, as are those of humans, contain both rods and cones. In parts of human retina, the rods and cones are intermingled and the nervous system provides a switching mechanism that permits adjustment for light conditions. In nocturnal animals, the optical arrangement of the eyes suggests that resolution is scarified for high light-gathering power. For example, in animals such as dog, the lens is large, that is, it has a short focal length. In diurnal animals, the lens is smaller and the front surface is flatter. Thus the focal length is longer and so the image on the retina is larger and dimmer than in the nocturnal eye. As a result, the resolution is improved. The retinas of diurnal animals, have localized areas having a high density of cone cells. In nocturnal animals, the retina is mainly made of rod cells. Rhodopsin, a photosensitive pigment, present in rods is declourised by photons and slowly regenerated in the dark. This ensures better vision for them in dim light.

WHAT CAUSES COOLING WHEN GLUCOSE IS DISSOLVED IN WATER?

Formation of a solution is a physico-chemical process. When two substances mix to form a solution, heat is either absorbed or released. This depends on various interactions taking place between the solvent and the solute at the molecular level. Glucose exists in a crystalline form. When dissolved in water, the crystal structure is broken. To break the bonds in the crystal energy is required. This is obtained from the water itself and so its temperature is reduced. Chemists call this an endothermic process. But considering a similar reaction, the dissolution of salt in water. Though this is also an endothermic process the heat transfer involved is very less. Strong exothermic effects are observed in certain cases where the substances interact strongly with water molecules. For example, dissolution of washing soda or sodium hydroxide.

WHY DO PLASTICS BECOME BRITTLE WHEN EXPOSED TO THE SUN FOR A LONG PERIOD?

Plastics are made of polymers which are giant molecules having long chains of repeating units derived from short molecules. These long chains are entangled with one another and held together by weak interatomic forces such as Vander Waals force. These weak bonds can be easily broken up by sunlight and so long exposures to sunlight makes them brittle.

WHY ARE SOAP BUBBLES AND OIL LAYERS COLOURED?

Coloured bands on soap bubbles and oil layers are caused by interference of light waves with themselves. Sunlight is a composite of seven colours each of which lies in a specific wavelength range. For ex. Violet light has a wavelength of 380 nanometres and red, above 600nm. Light waves falling on any thin film are partially reflected from the top and bottom surfaces of the film. A wave reflected from the bottom surface has to travel a longer distance than the one reflected from the top. This difference in distance traveled by the waves, called path difference, leads to a difference in the phases of the light waves. This phase difference depends on the thickness of the film at the point of reflection and angle of viewing. If the waves are ‘out of phase’, then they cancel each other and if they are ‘ in phase’ they add up. Thus the regions of the spectrum, which interfere constructively can be seen whereas those which interfere destructively are lost. Even if there is a slight variation in the thickness of the film, it will be coloured differently.

WHY DO RUNNERS RUN IN ANTI-CLOCKWISE DIRECTION?

As the heart is on the left side, for humans and animals, running anticlockwise makes the centrifugal force in the body to act from left to right. Whereas it is from right to left for clockwise running. Superior venecava takes blood to the heart aided by heart suction. This vein carries blood from left to right. Centrifugal force due to anticlockwise running helps this suction. If we run clockwise, the centrifugal force impedes suction. That is why, in olden days, health officers ensured that all carnival merri-go-rounds were run only in the anti-clockwise direction. Racing tracks, animal shows in circuses, bullock-drawn pelt on wheels, all mostly have only left turns. Stairways in temple towers have only left turns for going up. Clockwise running tires people, especially children easily.

WHY DOES THE TOUCH-ME-NOT PLANT SHRINK WHEN TOUCHED?

The touch-me-not plant shrinks within a few minutes of being touched. This is due to the loss of turgidity by cells within the pulvini-specialised motor organs at leaf joints. Upon stimulation the leaf cells lose potassium ions which causes water to leave the cells by osmosis. It takes about 10 minutes for the cells to regain turgidity and the leaflets to open out.

WHY DO VEGETABLES SUCH AS CUCUMBER, SNAKE GOURD AND BOTTLE GOURD SOMETIMES TASTE BITTER?

Bitterness in cucumber and other cucurbitaceae vegetables is due to the presence of compounds called cucurbitacins. Chemically these are tetracyclic triterpenes having high oxidative levels. They occur in nature as free glucosidesor as complicated mixtures, at high concentrations, in fruits and roots, for example in a wild variety of cucumber called cucumis hardwikii. High temperature above 92 degrees has been implicated in the increase of bitterness in fruits, although there is no evidence to support this. Conversely more bitter cucumbers are seen growing during the cooler growing season.

WHY DO BIRDS NEVER FALL OFF THEIR PERCHES WHEN SLEEPING. DO THEY, INFACT SLEEP?

Birds have nifty tendon arrangement in their legs. The flexor tendon from the muscle in the thigh reaches down the leg, round the ankle and then under the toes. This arrangement means that, at rest, the bird’s body weight causes the bird to bend its knee and pull the tendon tight, so closing the claws. Apparently this mechanism is so effective that dead birds have been found grasping their perches long after they have died.

WHY IS IT THAT THE EARLIEST SUNRISE AND LATEST SUNSET DO NOT COINCIDE WITH THE LONGEST DAY OF THE YEAR?

The time of rising and setting of any celestial body is a function of its position in the sky defined by right ascension and declination in the celestial coordinate system, position of the observer on the earth and the zenith distance of the body adopted to define phenomena. Due to earth’s motion in its orbit around the sun, the geocentric right ascension of the sun increases at the rate of 1 degree per day with slight variation during the course of the year. However, the declination of the sun varies from about 23.5 degree south in winters to 23.5 degree north in summer during the course of the year. The rate at which the declination varies changes very much from about 0.4 degree on vernal equinox to 0 degree on summer and winter solstices. The longest day occurs in the northern hemisphere when the declination of the sun is maximum north on summer solstice. Around the time the daily rate of change in declination goes through zero value. Therefore, around this time the rising and setting times are affected mainly due to change in right ascension which can be about ½ degree from sunrise to sunset. It is for this reason that earliest sunrise does not coincide with latest sunset for a given place. The difference is more pronounced for places in lower latitudes on earth over which the diurnal path of sun is at a greater inclination to the horizon and its motion in right ascension takes it more to the east, away from the horizon.