Archives June 2013

"No other symbol so strongly identifies the doctor than a stethoscope." Ariel Rogun, MD, PhD Although physician Rene Laennec (1781-1826) is credited with inventing the stethoscope, doctors in ancient Greece had practiced the art of auscultation, or listening. The Frenchman's flash of inspiration came in 1816 when he was confronted by a plump, young female patient with a heart condition. Overcome by embarrassment at the thought of having to press his ear to her ample bosom, Laennec recalled having seen children tapping a log while listening at the far end. This inspired him to roll up a sheath of papers into a cylinder and apply it to her chest, with the result that he could clearly hear her heartbeat. From this idea Laennec developed the first true stethoscope, which consisted of a hollow wooden tube around 9 inches (22 cm) long and 1 inch (2.5 cm) in diameter, known as a more...

In the fifteenth century Korea was a drought-plagued realm, and King Sejong (1397-1450) wished to levy land taxes based on an assessment of each farmer's potential harvest. To this end a nationwide network of rain gauges was established and the local magistrates of every village were commanded to report the rainfall to the central government. In 1441 each village was provided with a standard cylindrical container, 17 inches (43 cm) high and 7 inches (17 cm) wide, that was mounted on a stone stand; a special ruler was used to measure the depth of rainwater that entered the gauge over a specific time. Its inventor was a civil-servant scientist, Jang Yeong-Sil. Needless to say, the method of rain measurement was rather labor-intensive. The Chinese, meanwhile, had used a similar technique to measure snowfall in 1247C.E. In 1662 Sir Christopher Wren (1632-1723) invented the "pluviometer," a mechanical, self-emptying, tipping-bucket rain gauge. more...

The jointed prosthetic limb originated in the 1500s and steadily improved in the next five centuries. Credit for the invention goes to Ambroise Pare (circa 1510-1590), a French barber-surgeon better known for some of his earlier achievements. For example, during the siege of Turin (1536-37) he realized that gunshot wounds were not poisonous and did not need to be cauterized with boiling oil. In his book of 1545, La Method de traicter les playes faites par les arquebuses et aultres bastons a feu (The Method of Treating Wounds Made by Arquebuses and Other Guns), Pare recommended simple dressings and ointments. The Frenchman also promoted the tying off of blood vessels to prevent hemorrhage during surgery (ligaturation), which had been practiced for more than a thousand years but had fallen into disuse. Pare then invented a prosthetic limb for above- the-knee amputees, to be fitted to the thigh. It incorporated a more...

The process for fixing nitrogen from ammonia into nitric acid was a key development in the industrial production of fertilizers and explosives. It was patented in 1902 by Russian-German chemist Wilhelm Ostwald (1853-1932). One of the founders of the field of physical chemistry, Ostwald received the 1909 Nobel Prize in Chemistry for his work on catalysis, chemical equilibria, and reaction velocities. His process remains fundamental to the modern chemical industry. During the Ostwald Process, ammonia is heated in the presence of a platinum-rhodium catalyst to form nitric oxide, which is then oxidized to yield nitrogen dioxide, which in turn reacts with water to produce nitric acid and nitric oxide. Ostwald's major breakthrough was his .discovery that the length of time the reactants are in contact with the catalyst affects the yield of the ''reaction. Leave them there too long, and the nitric acid degrades back into nitrogen. Ostwald passed the more...

Velcro is the brand name for a lightweight, durable, and washable fastening, widely used instead of zips in clothing and luggage. It consists of two strips of nylon fabric, one densely covered in small, strong hooks and the other containing small loops. When pressed together, the two strips form a strong bond that can be peeled apart again, making a characteristic ripping noise, but will not open if pulled in any other direction. Swiss engineer George de Mestral (1907-1990) had The idea for Velcro in 1941 after getting his microscope out to Study the burrs stuck to his dog's fur and his own clothing, following a hike in the Alps. Burrs— seedheads of the burdock plant—have lots of strong little hooks that fix onto passing animals (and walkers) and stay tenaciously attached until the animal cleans them off, usually depositing them some distance from the parent plant. De Mestral saw more...

In 1938, Howard Florey (1898-1968) and Ernst Chain (1906-1979), two pathologists working at the University of Oxford, read a paper published nine years earlier about a substance called penicillin. Its author, Alexander Fleming, recounted how spores of the mold Penicillium notatum had entered his bacterial culture dishes and killed some of the bacteria. Florey and Chain recognized the significance of Fleming's observation and obtained a culture of the original mold. Initially they encountered difficulties in obtaining enough penicillin, but Norman Heatley (1911-2004), a biochemist on the team, devised ways of isolating penicillin without destroying it. Monitoring the extracted penicillin on mice infected with bacteria, they found animals treated with penicillin survived, while untreated animals died. With World War II now underway, the group recognized penicillin's enormous potential to treat war wounds. In 1941 Heatley traveled to the United States to start the commercial production of penicillin. Working with a team more...

"Sherlock Holmes took his... hypodermic syringe from its neat morocco case."   Sir Arthur Conan Doyle, The Sign of The Four (1890) In 1853 the first practical hypodermic syringe, capable of penetrating the skin without the need for a prior         incision, was developed simultaneously by the French surgeon Charles Gabriel Pravaz (1791-1853) working in Lyon, France, and Scottish physician Alexander Wood (1817-1884). Pravaz's silver syringe included a piston with a screw adjustment to measure the administration of precise doses of blood-coagulating agents in treating aneurysms. Wood used a glass syringe that allowed him to monitor visually the injection of morphine in his treatment of patients with neuralgic disorders: Wood later added a graduated scale for more precise measurements. The syringe permitted for the first time the intravenous administration of anesthesia and helped eliminate many of the difficulties faced in the still experimental realm of blood transfusions. more...

Last Sunday, I saw a very interesting hockey match. It was played between the Khalsa School and Guru Har Krishan Public School. Mr. Dhyan Chand and Balbir Singh acted as referees. It was played at Ram Lila Grounds. A large number of students and teachers had come to see the match. The referee gave long whistles and the captains of both the teams came forward. A coin was tossed in the air. The Khalsas won the toss and chose their favourable side. Both the teams were in their proper uniforms. The Khalsa players had blue shirts and white shorts while the players of Guru Har Krishan Public School had white shirts and white shorts. The match started at 3 PM. It was quite brisk from the  very beginning The Khalsas pressed hard but could not score a goal. They got two short corners but failed to score. Their centre forward more...

During the early 1970s, sounds generated by the electronic synthesizer became increasingly popular in recordings and at rock concerts. Gradually, these once prohibitively expensive musical instruments became commonplace and affordable. In addition to a great variety of user-friendly electronic keyboards on offer, there were related devices, such as sequencers, that could "trigger" sounds from a connected keyboard, as well as drum machines with a variety of sounds. One problem that arose with this electronic proliferation was that devices produced by different manufacturers tended not to be compatible with each other. American audio engineer Dave Smith sought a way forward when, at a 1981 meeting of the Audio Engineering Society, he presented a paper that proposed the first universal communication standard for musical equipment. He called it MIDI—an acronym for Musical Instrument Digital Interface. In essence, MIDI is a digital "language" that enables synthesizers, MIDI recorders (whether hardware sequencers or computer-based more...

"When tillage begins, other arts follow. The farmers therefore are the founders of human civilization" Daniel Webster, American statesman, 1840 English farmer Jethro Tull (1674-1741) despaired at the waste of seeds that resulted from sowing them by scattering. Seeds would fall too close together, or onto stony ground, lie at differing depths, and plants would grow with no soil between them from which the crop could be weeded, tended, and harvested. Tull's horsedrawn wooden seed drill improved on this situation and resulted in crop yields of up to eight times those where the seeds had been scattered. A shaped wooden drill dug an even groove of the right depth into the soil and seeds from the hopper mounted above it trickled into the groove, evenly spaced by the forward movement of the horse. Tull mounted three drills alongside each other in the machine, and so could plant three rows of more...


Archive


You need to login to perform this action.
You will be redirected in 3 sec spinner

Free
Videos