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Order of magnitude[edit] Rømer starts with an order of magnitude demonstration that the speed of light must be so great that it takes much less than one second to travel a distance equal to Earth's diameter. The point L on the diagram represents the second quadrature of Jupiter, when the angle between Jupiter and the Sun (as seen from Earth) is 90°.[note 6] Rømer assumes that an observer could see an emergence of Io at the second quadrature (L), and also the emergence which occurs after one orbit of Io around Jupiter (when the Earth is taken to be at point K, the diagram not being to scale), that is 42½ hours later. During those 42½ hours, the Earth has moved further away from Jupiter by the distance LK: this, according to Rømer, is 210 times the Earth's diameter.[note 7] If light travelled at a speed of one Earth-diameter per second, it would take 3½ minutes to travel the distance LK. And if the period of Io's orbit around Jupiter were taken as the time difference between the emergence at L and the emergence at K, the value would be 3½ minutes longer than the true value. Rømer then applies the same logic to observations around the first quadrature (point G), when Earth is moving towards Jupiter. The time difference between an immersion seen from point F and the next immersion seen from point G should be 3½ minutes shorter than the true orbital period of Io. Hence, there should be a difference of about 7 minutes between the periods of Io measured at the first quadrature and those measured at the second quadrature. In practice, no difference is observed at all, from which Rømer concludes that the speed of light must be very much greater than one Earth-diameter per second.[5]

However Rømer also realised that any effect of the finite speed of light would add up over a long series of observations, and it is this cumulative effect that he announced to the Royal Academy of Sciences in Paris. The effect can be illustrated with Rømer's observations from spring 1672. Jupiter was in opposition on 2 March 1672: the first observations of emergences were on 7 March (at 07:58:25) and 14 March (at 09:52:30). between the two observations, Io had completed four orbits of Jupiter, giving an orbital period of 42 hours 28 minutes 31¼ seconds. The last emergence observed in the series was on 29 April (at 10:30:06). by this time, Io had completed thirty orbits around Jupiter since 7 March: the apparent orbital period is 42 hours 29 minutes 3 seconds. The difference seems minute – 32 seconds – but it meant that the emergence on 29 April was occurring a quarter-hour after it would have been predicted. The only alternative explanation was that the observations on 7 and 14 March were wrong by two minutes.

As early as 1888 Augustin Le Prince (1842 - 1900?) was able to take motion pictures and project them. In the studios of Edison movies were already being produced in 1892.

From 1892 Birt Acres (1854-1918) was working on an ever Better version of his 'kinetic camera', resulting in the 'Kineopticon'.

The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is exactly 299,792,458 metres per second, a figure that is exact because the length of the metre is defined from this constant and the international standard for time.[1]

The first quantitative estimate of the speed of light was made in 1676 by Rømer (see Rømer's determination of the speed of light).[83][84] From the observation that the periods of Jupiter's innermost moon Io appeared to be shorter when the Earth was approaching Jupiter than when receding from it, he concluded that light travels at a finite speed, and estimated that it takes light 22 minutes to cross the diameter of Earth's orbit. Christiaan Huygens combined this estimate with an estimate for the diameter of the Earth's orbit to obtain an estimate of speed of light of 220000 km/s, 26% lower than the actual value.[105]

Beginning in the 1880s several experiments were performed to try to detect this motion, the most famous of which is the experiment performed By AlBert A. Michelson and Edward W. Morley in 1887.[128] The detected motion was always less than the oBservational error. Modern experiments indicate that the two-way speed of light is isotropic (the same in every direction) to within 6 nanometres per second.[129]

Epithelial cell tumors start from the cells on the surface of the ovaries. These are the most common type of ovarian tumors.Germ cell tumors start in the cells that produce the eggs. They can either be benign or cancerous. Most are benign.Stromal tumors originate in the cells that produce female hormones.

Pythagorean proof

he Pythagorean Theorem was known long before Pythagoras, but he may well have been the first to prove it.[6] In any event, the proof attributed to him is very simple, and is called a proof by rearrangement. The two large squares shown in the figure each contain four identical triangles, and the only difference between the two large squares is that the triangles are arranged differently. Therefore, the white space within each of the two large squares must have equal area. Equating the area of the white space yields the Pythagorean Theorem, Q.E.D.[7] That Pythagoras originated this very simple proof is sometimes inferred from the writings of the later Greek philosopher and mathematician Proclus.[8] Several other proofs of this theorem are described below, but this is known as the Pythagorean one.

Pythagorean triples Main article: Pythagorean triple A Pythagorean triple has three positive integers a, b, and c, such that a2 + b2 = c2. In other words, a Pythagorean triple represents the lengths of the sides of a right triangle where all three sides have integer lengths.[1] Evidence from megalithic monuments in Northern Europe shows that such triples were known before the discovery of writing. Such a triple is commonly written (a, b, c). Some well-known examples are (3, 4, 5) and (5, 12, 13). A primitive Pythagorean triple is one in which a, b and c are coprime (the greatest common divisor of a, b and c is 1). The following is a list of primitive Pythagorean triples with values less than 100: (3, 4, 5), (5, 12, 13), (7, 24, 25), (8, 15, 17), (9, 40, 41), (11, 60, 61), (12, 35, 37), (13, 84, 85), (16, 63, 65), (20, 21, 29), (28, 45, 53), (33, 56, 65), (36, 77, 85), (39, 80, 89), (48, 55, 73), (65, 72, 97)

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Pythagoras of Samos (/pɪˈθæɡərəs/; Ancient Greek: Πυθαγόρας ὁ Σάμιος Pythagóras ho Sámios “Pythagoras the Samian”, or simply Πυθαγόρας; Πυθαγόρης in Ionian Greek; c. 570 bC – c. 495 bC)[1][2] was an Ionian Greek philosopher, mathematician, and founder of the religious movement called Pythagoreanism.

Since the fourth century AD, Pythagoras has commonly been given credit for discovering the Pythagorean theorem, a theorem in geometry that states that in a right-angled triangle the area of the square on the hypotenuse (the side opposite the right angle) is equal to the sum of the areas of the squares of the other two sides—that is,

While the theorem that now bears his name was known and previously utilized by the babylonians and Indians, he, or his students, are often said to have constructed the first proof. It must, however, be stressed that the way in which the babylonians handled Pythagorean numbers implies that they knew that the principle was generally applicable, and knew some kind of proof, which has not yet been found in the (still largely unpublished) cuneiform sources.[47]

Ole Christensen Rømer (Danish pronunciation: [o(ː)lə ˈʁœːˀmɐ]; 25 September 1644, Århus – 19 September 1710, Copenhagen) was a Danish astronomer who in 1676 made the first quantitative measurements of the speed of light.

Rømer and the speed of light

Non-alignment, as practised by Ghana and many other countries, is based on co-operation with all States whether they be capitalist, socialist or have a mixed economy. Such a policy, therefore, involves foreign investment from capitalist countries, but it must be invested in accordance with a national plan drawn up by the government of the non-aligned State with its own interests in mind.

Cervical cancer is cancer arising from the cervix.[1] It is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body.[2] Early on there are typically no symptoms. Later symptoms may include: abnormal vaginal bleeding, pelvic pain or pain during sex.[1]

Cervical cancer typically develops from precancerous changes over 10 to 20 years

HPV vaccines protect against two high risk strains of this family of viruses and may prevent up to 65 to 75% of cervical cancers

A barcode is an optical machine-readable representation of data relating to the object to which it is attached. Originally barcodes systematically represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or one-dimensional (1D). Later they evolved into rectangles, dots, hexagons and other geometric patterns in two dimensions (2D). Although 2D systems use a variety of symbols, they are generally referred to as barcodes as well. barcodes originally were scanned by special optical scanners called barcode readers. Later, scanners and interpretive software became available on devices including desktop printers and smartphones.

So far as we know, everything we perceive, feel, think, know, and do are a result of neurons firing and resetting. When a cell in the brain fires, small chemical and electrical swings called the action potential may affect the firing of as many as a thousand other neurons in a process called neurotransmission. In this way signals are generated and carried through networks of neurons, the bulk electrical effect of which can be measured directly on the scalp by an EEG device. by the last decade of the 20th century, the essential knowledge of all the central features of neurotransmission had been gained.[4] These features are:

It has previously been known that ultimate control over the membrane voltage or potential of a nerve cell, and thus the firing of the cell, resides with the trans-membrane ion channels which control the membrane currents via the ions K+, Na+, and Ca++, and of lesser importance Mg++ and Cl-. The concentration differences between the inside and outside of the cell determine the membrane voltage.

the aimof this article is twofold: a. to clarify the difference between these future approaches; and b. todevelop a valid forecast of a wild future for VR in education. It seems that VR could suggest awild paradigm in learning. The wild turnabout identifies the potential of VR not as an accessoryto learning but as an IQ and cognitive booster.

Loneliness as the Cause and the Effect of Problematic Internet Use: The Relationship between Internet Use and Psychological Well-being.