My Science School

The moisture in the air is the result of the evaporation of water by the heat of the Sun. The amount of evaporation depends on the quantity of water and the intensity of the Sun’s heat. Another fact that contributes to the increase of atmospheric moisture is the breathing of living creatures. All these factors combine to produce enormous quantities of water vapour which are continuously rising from the surface of the land and the sea and condensing in the atmosphere. When this happens the vapour turns into clouds of various types.

It was not until 1803 that clouds began to be classified scientifically. Luke Howard published a paper on clouds and the Latin terms which he used became the basis of the internationally accepted cloud classification. Further work was carried out towards the end of the century and the development of aviation stimulated further research. Clouds have been classified into three main groups by international agreement. The classification depends on the height of the clouds above sea-level. The groups are: cirrus, cirrocumulus, cirrostratus, between 2,000 and 7,000metres; stratocumulus, stratus, below 2,000 metres. There are clouds that build up like pillars from the land into sky to a height of over 6,000 metres. These include cumulus and comulonimbus.

When the condensation of water vapour in the atmosphere goes beyond a certain limit, it turns rain or snow.

 

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As far back as 1665 a British scientist predicted that artificial fibres would one day be produced. The first experiments were carried out about 200 years later by a Swiss scientist in Lausanne and the first industrial production of the fibre took place in 1884 under the Frenchman Chardon net.

Naturally it took some time for the fibres to become popular. In the first decades of the twentieth century rayon was being produced from cellulose. Protein fibres, made from such natural materials as casein, in skimmed milk, peanuts and soya beans, were also produced.

Today, the production of synthetic resins has made artificial fibres into a vast industry. Its products include nylon, dralon, orlon and Dacron which are used all over the world.

 

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Everybody knows whether a sound is pleasant or unpleasant, loud or soft, mellow or sharp, but few people can actually explain what sound is and what are it qualities.

The string of a guitar or a harp is silent until it is plucked with the finger or a plectrum and set into vibration. The skin of a drum does not produce any sound until it is struck with a drumstick and made to vibrate. The sound of the saxophone is also produced by the vibration of its red. In a trumpet the noise comes from air that is thrust into the instruments and vibrated.

All sounds—the human voice, the noises made by animals, the tinkling of a bell or the buzzing of insects –is the result of vibration. Scientists have also discovered that there can be sound if there is no air to be vibrated.

An experiment was once carried out in which a bell was placed inside a glass jar. As soon as all the air was removed from the jar the ringing of the bell could no longer be heard.

Astronauts have confirmed that there is absolute silence in space.

It is easy, therefore, to see that sound spreads through the atmosphere like waves or ripples that spread outwards in a pond when something drops into it.

 

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You do most of your dreaming during REM sleep. But your brain paralyzes your muscles so you do not act out the dreams.

During sleep, a person usually progresses through the 3 stages of non-REM sleep before entering REM sleep. This takes about 1 to 2 hours after falling asleep. The cycle is repeated three to four times each night. An adult spends more time in NREM sleep than in REM sleep. An infant usually spends about half of the sleeping time in NREM and half in REM stages.

Dreams happen during the rapid eye movement (REM) stage of sleep. In a typical night, you dream for a total of two hours, broken up by the sleep cycle.2

Researchers do not fully understand the exact reasons why we sleep. They do know that newborns dream and that depriving rats of REM sleep greatly shortens their lives. Other mammals and birds also have REM sleep stages, but cold-blooded animals such as turtles, lizards, and fish do not.

 

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Trans-Neptunian objects (TNO) are any solar system minor planet that orbits the sun at a greater average distance than Neptune. Pluto is now considered a TNO, as is Eris. As of July 2014, over 1,500 trans-Neptunian objects have been cataloged and of these, some 200 have been designated as dwarf planets. From Earth, astronomers study TNO heat emissions, colors, and spectra.The Kuiper Belt is a region beyond the orbit of Neptune at 30 Astronomical Units (AU) to about 50 AU from the sun. It is sometimes called the Edgeworth–Kuiper Belt . The Kuiper Belt is much larger than the Asteroid Belt. It’s about twenty times as wide and twenty to two hundred times as massive. Kuiper Belt objects, called KBOs , are composed of rock and metal, like the asteroids, but also frozen ices like ammonia, methane, and water. Trans-Neptunian objects are Kuiper Belt objects (KBOs), but KBOs are not TNOs because the distance range of KBOs from the sun is much farther out in the solar system.

Studying colours and spectra provides insight into the objects' origin and a potential correlation with other classes of objects, namely centaurs and some satellites of giant planets (Triton, Phoebe), suspected to originate in the Kuiper belt. However, the interpretations are typically ambiguous as the spectra can fit more than one model of the surface composition and depend on the unknown particle size. More significantly, the optical surfaces of small bodies are subject to modification by intense radiation, solar wind and micrometeorites. Consequently, the thin optical surface layer could be quite different from the regolith underneath, and not representative of the bulk composition of the body.

 

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Triton is the largest of Neptune's moons. Discovered in 1846 by British astronomer William Lassell — just weeks after Neptune itself was found — the moon showed some strange characteristics as astronomers learned more about it.

Like our own moon, Triton is locked in synchronous rotation with Neptune?one side faces the planet at all times. But because of its unusual orbital inclination both Polar Regions take turns facing the Sun.

Triton has a diameter of 1,680 miles (2,700 kilometers). Spacecraft images show the moon has a sparsely cratered surface with smooth volcanic plains, mounds and round pits formed by icy lava flows. Triton consists of a crust of frozen nitrogen over an icy mantle believed to cover a core of rock and metal. Triton has a density about twice that of water. This is a higher density than that measured for almost any other satellite of an outer planet. Europa and Io have higher densities. This implies that Triton contains more rock in its interior than the icy satellites of Saturn and Uranus.

Triton's thin atmosphere is composed mainly of nitrogen with small amounts of methane. This atmosphere most likely originates from Triton's volcanic activity, which is driven by seasonal heating by the Sun. Triton, Io and Venus are the only bodies in the solar system besides Earth that are known to be volcanically active at the present time.

Triton is named after the son of Poseidon (the Greek god comparable to the Roman Neptune). Until the discovery of the second moon Nereid in 1949, Triton was commonly known as simply "the satellite of Neptune."

 

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Ghrelin is a hormone that is produced and released mainly by the stomach with small amounts also released by the small intestine, pancreas and brain.

Ghrelin has numerous functions. It is termed the ‘hunger hormone’ because it stimulates appetite, increases food intake and promotes fat storage. When administered to humans, ghrelin increases food intake by up to 30%; it circulates in the bloodstream and acts at the hypothalamus, an area of the brain crucial in the control of appetite. Ghrelin has also been shown to act on regions of the brain involved in reward processing such as the amygdala.

Ghrelin also stimulates the release of growth hormone from the pituitary gland, which, unlike ghrelin itself, breaks down fat tissue and causes the build-up of muscle.

Ghrelin also has protective effects on the cardiovascular system and plays a role in the control of insulin release. 

Eating reduces concentrations of ghrelin. Different nutrients slow down ghrelin release to varying degrees; carbohydrates and proteins restrict the production and release of ghrelin to a greater extent than fats.

Somatostatin also restricts ghrelin release, as well as many other hormones released from the digestive tract.

 

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If there is one thing that accompanies each and every one of us everyone of us every time we step out in the day time, it is our shadows. While shadows are easily observed in the daytime, they can be even when it gets dark. If a light source is available.

Shadow, as you would have learnt, are dark areas created when light from a source has been blocked by an opaque (solid) object. As our body blocks some of the sun’s light when we are out and about, it creates shadows as the lights can’t shine through our bodies.

The long and short of it

The length of our shadows changes as the sun rises and sets. While it is bigger and longer when the sun is near the horizon (as we block more light), it is much smaller when the sun is shining from high above us. Have you, however, ever wondered if our shadows can completely disappear?

While they do disappear when there is no light source, there is a special case that will be of interest. In this case, our shadows vanish, even when the sun is still shining. This is popularly referred to as zero shadow day.

Zero shadow days

A zero shadow is an astronomical event that takes place when the sun is exactly overhead, or at zenith, to a specific location. At noon on such days, no object will have a shadow as the sun rays hit the surface perpendicularly.

Zero shadow day occurs twice each year for given place, but not in all locations. For a place to enjoy zero shadow days, its latitude has to be between the Tropic of Cancer (23.5 degrees north of the equator) and Tropic of Capricorn (23.5 degrees south of the equator).

Differs from place to place

Keep in mind that even within these latitudes, the dates will be different for different regions. There are plenty of sources online to help you figure out when zero shadow days will happen where you live. You can also ask your teachers and family members for help. And when you know the dates, make sure you see you know the dates, make sure you see your shadow disappear if your place experiences the phenomenon!

 

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The Fertile Crescent is a crescent-shaped region in the Middle East, spanning modern-day Iraq, Syria, Lebanon, Palestine, Israel, Jordan, and Egypt, together with the southeastern region of Turkey and the western fringes of Iran. Some authors also include Cyprus.

The region is one of the cradles of civilization because it is where settled farming first emerged as people started the process of clearance and modification of natural vegetation in order to grow newly domesticated plants as crops. Early human civilizations such as Sumer in Mesopotamia flourished as a result. Technological advances in the region include the development of agriculture and the use of irrigation, of writing, the wheel, and glass, most emerging first in Mesopotamia.

The main types of grain that were used for agriculture were wheat, barley, millet, and emmer. Rye and oats were not yet known for agricultural use. In Babylonia, Assyria, and the Hittite lands, barley was the main grain for human use: It was a widely used form of payment, and flat bread was made from barley. The smallest unit of weight was the equivalent of one grain (1/22 g). Beer and luxury foods were made from wheat and emmer.

Other agricultural products include sesame (derived from the Akkadian word šamaššammu), which was widely cultivated and used to make oil. Olive oil was produced in the mountains. Flax was used to make linen cloth. Peas were cultivated in Mesopotamia, while lentils were preferred in Palestine. Figs, pomegranate, apple, and pistachio groves were found throughout the Fertile Crescent. In villages and cities of southern Mesopotamia groves of date palms were common. The dates were eaten either fresh or dried, and palm wood was also used in crafts, but not in construction.

 

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Palynology is the study of pollen grains produced by seed plants (angiosperms and gymnosperms) and spores (pteridophytes, bryophytes, algae and fungi). Pollen and spores differ in their function, but both result from cell division involving a reduction by half of the chromosome content (meiosis) (Moore et al. 1991). Pollen grains house the male gametes, but spores are usually the resting or dispersal phase of the fern, algae, etc. Because of the larger size and the importance of pollen in pollination and to insects, pollen will be emphasized.

Pollen grains vary in shape from spherical to elliptic to triangular. Most pollen grains range from about 4 to 250 ìm. Pollen grains often have openings (pores) or furrows (colpus = singular, colpi = plural). A pollen grain with one colpus is called monocolpate. A pollen grain with three pores is triporate and one with three pores within three colpi is termed tricolporate. The outside layer of the pollen grain can be smooth (psilate), net-like (reticulate), or looks like a ball of string (striate). Some pollen grains even have spine like projections (echinate).

It is common knowledge that pollen is a major cause of allergies. However, pollen can be used to determine insect migration, insect food sources, honey types and in forensics, climatic changes, etc. There are several reasons pollen is used in these studies. First, pollen grains are distinctive, easily recognizable and identifiable to the family, genus and often species rank. Thus, very specific information can be obtained. Second, pollen is made up of sporopollenin that is durable and does not easily decay. Third, from the identification of the pollen, the geographical origin of the plant from which the pollen came can be determined.

 

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Taking root around 12,000 years ago, agriculture triggered such a change in society and the way in which people lived that its development has been dubbed the "Neolithic Revolution." Traditional hunter-gatherer lifestyles, followed by humans since their evolution, were swept aside in favor of permanent settlements and a reliable food supply. Out of agriculture, cities and civilizations grew, and because crops and animals could now be farmed to meet demand, the global population rocketed — from some five million people 10,000 years ago, to more than seven billion today.

There was no single factor, or combination of factors, that led people to take up farming in different parts of the world. In the Near East, for example, it's thought that climatic changes at the end of the last ice age brought seasonal conditions that favored annual plants like wild cereals. Elsewhere, such as in East Asia, increased pressure on natural food resources may have forced people to find homegrown solutions. But whatever the reasons for its independent origins, farming sowed the seeds for the modern age.

Cattle, goats, sheep and pigs all have their origins as farmed animals in the so-called Fertile Crescent, a region covering eastern Turkey, Iraq and southwestern Iran. This region kick-started the Neolithic Revolution. Dates for the domestication of these animals range from between 13,000 to 10,000 years ago.

Genetic studies show that goats and other livestock accompanied the westward spread of agriculture into Europe, helping to revolutionize Stone Age society. While the extent to which farmers themselves migrated west remains a subject of debate, the dramatic impact of dairy farming on Europeans is clearly stamped in their DNA. 

 

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A cultigen (from the Latin cultus – cultivated, and gens – kind) or cultivated plant is a plant that has been deliberately altered or selected by humans; it is the result of artificial selection. These anthropogenic plants, for the most part, have commercial value in horticulture, agriculture or forestry. Because cultigens are defined by their mode of origin and not by where they are growing, plants meeting this definition remain cultigens whether they are naturalised in the wild, deliberately planted in the wild, or growing in cultivation.

Notably, agriculture does not appear to have developed in particularly impoverished settings; domestication does not seem to have been a response to food scarcity or deprivation. In fact, quite the opposite appears to be the case. It was once thought that human population pressure was a significant factor in the process, but research indicated by the late 20th century that populations rose significantly only after people had established food production. Instead, it is thought that—at least initially—the new animals and plants that were developed through domestication may have helped to maintain ways of life that emphasized hunting and gathering by providing insurance in lean seasons. When considered in terms of food management, dogs may have been initially domesticated as hunting companions, while meat and milk could be obtained more reliably from herds of sheep, goats, reindeer, or cattle than from their wild counterparts or other game animals. Domestication made resource planning a more predictable exercise in regions that combined extreme seasonal variation and rich natural resource abundance.

 

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