Ivan Petrovich Pavlov (1849 - 1936)

-45085-2540 Ivan Pavlov was a Russian scientist most famous for describing the psychological phenomenon referred to as a "conditioned response"*. Pavlov made a number of other very important discoveries in the realm of physiology, particularly related to digestion*. Indeed, it was while studying the secretion of digestive enzymes that he became interested in the integration of the body and the brain.

Pavlov's first independent work focused on the physiology of the circulation of the blood. He studied the influence of variations in blood volume on blood pressure. He also investigated the nervous control of the heart.

For about 20 years starting from 1879 he studied how digestion works, revolutionizing our understanding of the process and the role of nervous system in nutrition. He discovered how different ferments and acids act on various stages of digestion to transform food into simpler components absorbed by the organism.

In 1897, Pavlov published his results and generalizations in a book called "Work of the Digestive Glands"*. For this work, he was the first Russian and physiologist to receive the Nobel Prize, which was awarded in 1904.

The final 35 years of Pavlov's research were devoted to the investigation of the conditioned reflex and the study of the brain. In the late 1920's, he began working with clinical patients, trying to understand the qualitative differences between the higher nervous processes of animals and of people.

The 'conditioning' model presented by Pavlov had an enormous influence on western behavioral psychology. For Pavlov, the assumption was that the unconscious processes that existed were simple reflexes which could be conditioned to affect behavioral change.

Ivan Petrovich Pavlov can be thanked for maintaining the purity of observational science and striving to keep the standards for experimental methodology at its highest level. Although he is most remembered for his groundbreaking work in behavioral psychology, the inspiring research that led Pavlov to these observations cannot be forgotten. He was a truly great scientist and researcher.

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*conditioned response – условный рефлекс

*digestion - пищеварение, переваривание пищи; усвоение пищи

*gland –железа

*unconscious - бессознательный, неосознанный

Leonardo Pisano Fibonacci (13th century)

Fibonacci was an Italian number theorist often referred to as Leonard of Pisa. Very little is known about him or his family and there are no photographs or drawings of him. Fibonacci was born in Italy but received education in North Africa. Through his experiences in North Africa, which no doubt included meeting merchants and learning their systems of applied arithmetic, he was introduced to the "Hindu-Arabic" system of numerals, the same one we all use today.

So when he returned to Pisa, he wrote a book about it that he finished in 1202. Titled Liber abbaci, meaning "Book of Calculating," the work dealt with the methods of arithmetic in the decimal system (now taught to all elementary school children) and it eventually persuaded European mathematicians to drop the old way in favor of the new one.

Fibonacci is considered to be one of the most talented mathematicians for the Middle Ages. He made many original contributions to complex calculations, algebra, and geometry, and pioneered number theory and indeterminate* analysis, discovering the Fibonacci series or Fibonacci sequence.

The series is 1, 1, 2, 3, 5, 8, 13, 21, 34, 55... This sequence shows that each number is the sum of the two preceding numbers. It is a sequence that is seen and used in many different areas of mathematics and science. The series is an example of a recursive (characterized by recurrence or repetition) sequence. The Fibonacci Series defines the curvature* of naturally occurring spirals, such as snail shells and even the pattern of seeds in flowering plants.

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*indeterminate – неизвестный, неопределенный

*curvature - выгиб, изгиб, искривление, кривизна

Edmond Halley (1656–1742)

Halley was a bold and restless prodigy, born to a wealthy family, who published three papers on astronomical subjects while still a college undergraduate. At the age of 20 he spent a year on the remote South Atlantic island of St. Helena, observing the skies of the southern hemisphere*. He returned to England and published the first catalogue of the southern stars. That achievement had earned him membership in the Royal Society by the age of 22.

In 1699 he sailed HMS* Paramour around the South Atlantic Ocean, taking readings of magnetic north wherever he went. That cruise was the first voyage ever made for a purely scientific purpose. From the data he collected, Halley produced the first map showing the variation of the Earth's magnetic field in 1700. So with that voyage he established not just new science, but a new way of doing science.

His interest in planetary motions led him to Isaac Newton whose new mathematics of the calculus, laws of physics, and theory of gravitation were being widely scorned and disputed. Halley was so convinced that he financed the publication of Newton's book Principia Mathematica in 1687 which put physics, astronomy, and science itself on a foundation that lasted until Einstein's modifications more than 200 years later.

Edmond Halley was the first man to recognize the recurring astronomical visitor now known as Halley's Comet. In 1705 he published Synopsis on Cometary Astronomy, in which he argued that prominent comets observed in 1531, 1607 and 1682 had all been the same comet, returning to pass Earth on a cycle of about 76 years. He was proven correct when the comet returned on Christmas Day of 1758 (though Halley himself had died in 1742), and the comet has since been known as Halley's Comet.

Halley became a professor at Oxford in 1704. Multitalented and exceedingly brainy, Halley also contributed to other scientific fields during his long career; he is especially known for inventing the diving bell*.

(Adapted from the Internet sites)