JOHN ARCHIBALD WHEELER
In 1990, Wheeler has suggested that information is fundamental to the physics of the universe. According to this 'it from bit' doctrine, all things physical are information-theoretic in origin.
Wheeler: It from bit. Otherwise put, every 'it'—every particle, every field of force, even the space-time continuum itself—derives its function, its meaning, its very existence entirely—even if in some contexts indirectly—from the apparatus-elicited answers to yes-or-no questions, binary choices, bits. 'It from bit' symbolizes the idea that every item of the physical world has at bottom—a very deep bottom, in most instances—an immaterial source and explanation; that which we call reality arises in the last analysis from the posing of yes–no questions and the registering of equipment-evoked responses; in short, that all things physical are information-theoretic in origin and that this is a participatory universe.
Wheeler was awarded the Wolf Prize in Physics in 1997.
Wheeler has speculated that the laws of physics may be evolving in a manner analogous to evolution by natural selection in biology. "How does something arise from nothing?", he asks about the existence of space and time (Princeton Physics News, 2006). He also coined the term "Participatory Anthropic Principle" (PAP), a version of a Strong Anthropic Principle. From a transcript of a radio interview on "The anthropic universe"
Wheeler: We are participators in bringing into being not only the near and here but the far away and long ago. We are in this sense, participators in bringing about something of the universe in the distant past and if we have one explanation for what's happening in the distant past why should we need more?Martin Redfern: Many don't agree with John Wheeler, but if he's right then we and presumably other conscious observers throughout the universe, are the creators — or at least the minds that make the universe manifest.
Monday, October 25, 2010
Thursday, June 10, 2010
UNUSUAL TYPE OF HYPERTHYROIDISM
They are three well_recognised forms of hyperthyroidism
1. Graves' diseases (diffuse toxic goiter offen associated with exophthalmos)
2.Plummer's diseases (toxic multinodular goiter )
3.Toxic uninodular goiter (toxic adenoma )
This three types of hyperthyroidism are usually recognised easily by careful physical examination and radioisotope thyroidal scanning when other less common forms of hyperthyroidism have been excluded.
Additional types of hyperthyroidism listed by Committee on Nomenclature of the American Thyroid Association, are only rarely recognised clinically.
We have observed examples of some of these uncommon forms of hyperthyroidism and several varieties not specifically listed by the Committee on Nomenclature.
Since the etiology of the hyperthyroidism and appropriate treatment are quite variable, recognition of these rare forms of a common disorder is important. Some of these clinically situations represent variation of the common forms of hyperthyroidism with aspects that are potentially confusing and diagnostically challenging.
The purpose of this report is to review these less common varieties of hyperthyroidism from our own experience and that reported by others.
Iodide-induced hyperthyroidism was first recognised following the widespread use of iodine for goiter prophylaxis.
In 1925 Kimball reported his experience of 309 patients in whom hyperthyroidism was thought to occur the following the administration of iodine.
Most of these patients had long-standing goiters which were clinically or microscopycally adenomatous (multinodular). He emphasized that hyperthyroidism seemed related to the addition of prophylactic amounts of iodine to salt in only six of this case(2%) and that all others had received large amount of iodine(5-10 drops of Lugol's solution per day ot its equivalent).
More recent report have suggested that even small amounts of iodine may cause hyperthyroidism when previous iodine deficiency was present.
The following case demonstratest that patients with multinodular goiters of long duration living in area without endemic iodine deficiency, may develop hyperthyroidism after receiving large doses of iodine.
SOURCE FROM:
http://journals.lww.com/md-journal/Citation/1973/05000/Unusual_Types_of_Hyperthyroidism.2.aspx
1. Graves' diseases (diffuse toxic goiter offen associated with exophthalmos)
2.Plummer's diseases (toxic multinodular goiter )
3.Toxic uninodular goiter (toxic adenoma )
This three types of hyperthyroidism are usually recognised easily by careful physical examination and radioisotope thyroidal scanning when other less common forms of hyperthyroidism have been excluded.
Additional types of hyperthyroidism listed by Committee on Nomenclature of the American Thyroid Association, are only rarely recognised clinically.
We have observed examples of some of these uncommon forms of hyperthyroidism and several varieties not specifically listed by the Committee on Nomenclature.
Since the etiology of the hyperthyroidism and appropriate treatment are quite variable, recognition of these rare forms of a common disorder is important. Some of these clinically situations represent variation of the common forms of hyperthyroidism with aspects that are potentially confusing and diagnostically challenging.
The purpose of this report is to review these less common varieties of hyperthyroidism from our own experience and that reported by others.
Iodide-induced hyperthyroidism was first recognised following the widespread use of iodine for goiter prophylaxis.
In 1925 Kimball reported his experience of 309 patients in whom hyperthyroidism was thought to occur the following the administration of iodine.
Most of these patients had long-standing goiters which were clinically or microscopycally adenomatous (multinodular). He emphasized that hyperthyroidism seemed related to the addition of prophylactic amounts of iodine to salt in only six of this case(2%) and that all others had received large amount of iodine(5-10 drops of Lugol's solution per day ot its equivalent).
More recent report have suggested that even small amounts of iodine may cause hyperthyroidism when previous iodine deficiency was present.
The following case demonstratest that patients with multinodular goiters of long duration living in area without endemic iodine deficiency, may develop hyperthyroidism after receiving large doses of iodine.
SOURCE FROM:
http://journals.lww.com/md-journal/Citation/1973/05000/Unusual_Types_of_Hyperthyroidism.2.aspx
Friday, June 4, 2010
PROF. EMMETT LEITH
Prof. Emmett Leith was born in Detroit, Michigan, on March 12, 1927, and received all three of his degrees, B.S., M.S. and Ph.D. in physics, from Wayne State University, in 1949, 1952, and 1978, respectively. He spent his entire 50-year professional career at the University of Michigan. He was first employed as a research assistant (1952–1956) and then promoted to a research associate (1956–1960) at Willow Run Laboratories (WRL). In 1960, his research group at WRL was moved to the University of Michigan Institute of Science and Technology where he became a research engineer. He was appointed an associate professor of electrical engineering in 1965 and promoted to full professor in 1968.
In 1963, Emmett and Upatnieks introduced the technique of diffuse illumination to demonstrate the first high-quality holograms of three-dimensional objects. In Emmett’s own words: “We … found that the images formed from such holograms produced startling images, fully 3-D, without the need for viewing with special glasses, and had all of the usual properties of actual objects, including full parallax. One could move one’s head and peer ehind obscuring structures to see what was hidden behind, just as if one were viewing the actual objects.” When they presented their results publicly at the Annual Optical Society of America Meeting in the spring of 1964, they created quite a sensation.
Emmett Leith was elected to the National Academy of Engineering in 1982. In addition to this honor, he received many awards, including the National Medal of Science (1979), the IEEE Morris Liebmann Memorial Award (1968), the Stuart Ballantine Medal of the Franklin Institute (1969), the R.W. Wood Prize of the Optical Society of America (1975), the Frederic Ives Medal of the Optical Society of America (1985), and the Gold Medal of the SPIE (1990). Emmett supervised the research of 43 Ph.D. students at Michigan, and he regularly taught a variety of courses on basic optics and optical signal processing.
Emmett’s work on SAR and holography had an enormous technical impact and was a major driving force in shaping the field of optical signal processing. In addition to his educational and scientific contributions, his work spurred many commercial applications that now comprise a multi-billion dollar industry. Emmett, a humble individual by nature, loved his work and remained active in his field until the time of his death.
THE MAN BEHIND HOLOGRAM TECHNOLOGY
Holography dates from 1947, when British / Hungarian scientist Dr. Dennis Gabor developed the theory of holography while working to improve the resolution of an electron microscope.
About Dr. Dennis Gábor(Adapted from his autobiography)Dr. Dennis Gábor(b. 1900, Budapest - d. 1979, London)Nobel Prize in Physics, 1971 for his investigation and development of holography.
Dr. Dennis Gábor was born in Budapest (Hungary) on 5 June 1900. He studied electrical engineering first in Budapest, later in Berlin from Techniscje Hochschule, where he finished his academic education with the award of Doctorate of Engineering in 1927. His doctorate work was the development of one of the first high speed cathode ray oscillographs and in the course of this, made the first iron-shrouded magnetic electron lens. In 1927 he joined Siemens & Halske AG Berlin, where he started investigations on gas discharges and plasmas. The most far reaching result of his six years with Siemens & Halske was his invention of the molybdenum tape seal, which is used to this day in all high-pressure quartz-mercury lamps. In what Dennis calls his “first lesson in serendipity,” he invented the mercury lamp while attempting to develop a cadmium lamp which proved unsuccessful.
In 1934 Gabor went to the British Thomson-Houston Co. Research Laboratory, Rugby, England, on an inventor’s agreement. . His work on gas discharge tubes gave him recognition in the BTH Research Laboratory where he remained until 1948. He also developed a system of stereoscopic cinematography, and in the last year at BTH carried out the basic experiments in holography, called “wave front reconstruction”.
On January 1, 1949 he joined the Imperial College of Science & Technology in London, first as a Reader in Electronics, and later as Professor of Applied Electron Physics, until 1967. From 1949-67 Gabor carried out some 20, mostly experimental, investigations with his Ph.D. assistants. They cleared up the “Langmuir Paradox”; the surprisingly fast apparent establishment of Maxwellian distributions of electrons in a low-pressure plasma, which had worried Gabor for 25 years. They also made a Wilson cloud chamber, in which the velocity of particles became measurable by impressing on them a high frequency, critical field, which produced time marks on the paths, at the points of maximum ionization. They also developed: a holographic microscope; a new electron-velocity spectroscope; an analogue computer which was a universal, non-linear “learning” predictor, recognizer and simulator of time series; a flat, thin color television tube; and a new type of thermionic converter. Theoretical work included communication theory, plasma theory, magnetron theory, and a scheme of fusion.
After his retirement in 1967 he remained connected with the Imperial College as a Senior Research Fellow and became Staff Scientist of CBS Laboratories, Stamford, Conn. where he collaborated with the President, life-long friend, and father of the color television, Dr. Peter C. Goldmark, in many new schemes of communication and display. Though he was always a passionate scientist and inventor, he was almost equally interested in social problems. In his spare time he wrote the books Inventing the Future (1963), Innovations (1970), and The Mature Society (1972).He wrote, “Though I still have much unfinished technological work on my hands, I consider this as my first priority in my remaining years.”(Editor’s Note: He passed away on 9 July 1979 in London.)
BRIEF HISTORY OF HOLOGRAM
1947: Denis Gabor invents theory of holography
1960: Invention of laser helps hologram development
1962: Leith and Upatnieks make first laser hologram of toy train and bird
1977: Royal Academy stages Light Fantastic show
2003: Stephen Benton, inventor of credit card holograms, dies
In 1963, Emmett and Upatnieks introduced the technique of diffuse illumination to demonstrate the first high-quality holograms of three-dimensional objects. In Emmett’s own words: “We … found that the images formed from such holograms produced startling images, fully 3-D, without the need for viewing with special glasses, and had all of the usual properties of actual objects, including full parallax. One could move one’s head and peer ehind obscuring structures to see what was hidden behind, just as if one were viewing the actual objects.” When they presented their results publicly at the Annual Optical Society of America Meeting in the spring of 1964, they created quite a sensation.
Emmett Leith was elected to the National Academy of Engineering in 1982. In addition to this honor, he received many awards, including the National Medal of Science (1979), the IEEE Morris Liebmann Memorial Award (1968), the Stuart Ballantine Medal of the Franklin Institute (1969), the R.W. Wood Prize of the Optical Society of America (1975), the Frederic Ives Medal of the Optical Society of America (1985), and the Gold Medal of the SPIE (1990). Emmett supervised the research of 43 Ph.D. students at Michigan, and he regularly taught a variety of courses on basic optics and optical signal processing.
Emmett’s work on SAR and holography had an enormous technical impact and was a major driving force in shaping the field of optical signal processing. In addition to his educational and scientific contributions, his work spurred many commercial applications that now comprise a multi-billion dollar industry. Emmett, a humble individual by nature, loved his work and remained active in his field until the time of his death.
THE MAN BEHIND HOLOGRAM TECHNOLOGY
Holography dates from 1947, when British / Hungarian scientist Dr. Dennis Gabor developed the theory of holography while working to improve the resolution of an electron microscope.
About Dr. Dennis Gábor(Adapted from his autobiography)Dr. Dennis Gábor(b. 1900, Budapest - d. 1979, London)Nobel Prize in Physics, 1971 for his investigation and development of holography.
Dr. Dennis Gábor was born in Budapest (Hungary) on 5 June 1900. He studied electrical engineering first in Budapest, later in Berlin from Techniscje Hochschule, where he finished his academic education with the award of Doctorate of Engineering in 1927. His doctorate work was the development of one of the first high speed cathode ray oscillographs and in the course of this, made the first iron-shrouded magnetic electron lens. In 1927 he joined Siemens & Halske AG Berlin, where he started investigations on gas discharges and plasmas. The most far reaching result of his six years with Siemens & Halske was his invention of the molybdenum tape seal, which is used to this day in all high-pressure quartz-mercury lamps. In what Dennis calls his “first lesson in serendipity,” he invented the mercury lamp while attempting to develop a cadmium lamp which proved unsuccessful.
In 1934 Gabor went to the British Thomson-Houston Co. Research Laboratory, Rugby, England, on an inventor’s agreement. . His work on gas discharge tubes gave him recognition in the BTH Research Laboratory where he remained until 1948. He also developed a system of stereoscopic cinematography, and in the last year at BTH carried out the basic experiments in holography, called “wave front reconstruction”.
On January 1, 1949 he joined the Imperial College of Science & Technology in London, first as a Reader in Electronics, and later as Professor of Applied Electron Physics, until 1967. From 1949-67 Gabor carried out some 20, mostly experimental, investigations with his Ph.D. assistants. They cleared up the “Langmuir Paradox”; the surprisingly fast apparent establishment of Maxwellian distributions of electrons in a low-pressure plasma, which had worried Gabor for 25 years. They also made a Wilson cloud chamber, in which the velocity of particles became measurable by impressing on them a high frequency, critical field, which produced time marks on the paths, at the points of maximum ionization. They also developed: a holographic microscope; a new electron-velocity spectroscope; an analogue computer which was a universal, non-linear “learning” predictor, recognizer and simulator of time series; a flat, thin color television tube; and a new type of thermionic converter. Theoretical work included communication theory, plasma theory, magnetron theory, and a scheme of fusion.
After his retirement in 1967 he remained connected with the Imperial College as a Senior Research Fellow and became Staff Scientist of CBS Laboratories, Stamford, Conn. where he collaborated with the President, life-long friend, and father of the color television, Dr. Peter C. Goldmark, in many new schemes of communication and display. Though he was always a passionate scientist and inventor, he was almost equally interested in social problems. In his spare time he wrote the books Inventing the Future (1963), Innovations (1970), and The Mature Society (1972).He wrote, “Though I still have much unfinished technological work on my hands, I consider this as my first priority in my remaining years.”(Editor’s Note: He passed away on 9 July 1979 in London.)
BRIEF HISTORY OF HOLOGRAM
1947: Denis Gabor invents theory of holography
1960: Invention of laser helps hologram development
1962: Leith and Upatnieks make first laser hologram of toy train and bird
1977: Royal Academy stages Light Fantastic show
2003: Stephen Benton, inventor of credit card holograms, dies
Thursday, May 20, 2010
SUBRAHMAYAN CHANDRASEKHAR
Subrahmanyan Chandrasekhar (1910-1995). Born in Lahore, then a part of British Colonial India, in 1910, theoretical astrophysicist Chandrasekhar was elected to the Academy only two years after he became a US citizen in 1953. Chandrasekhar was noted for his work in the field of stellar evolution, and in the early 1930s he was the first to theorize that a collapsing massive star would become an object so dense that not even light could escape it. Although this finding was greeted with some skepticism at the time it was announced, it went on to form the foundation of the theory of black holes, and eventually earned him a shared Nobel Prize in physics for 1983. In addition to his work on star degeneration, Chandrasekhar contributed important theorems on the stability of cosmic masses in the presence of gravitation, rotation, and magnetic fields; this work proved to be crucial for the understanding of the spiral structure of galaxies. From the time he came to the US in 1936 until his death in 1995, Chandrasekhar was affiliated with the University of Chicago and its Yerkes Observatory.
SOURCE FROM:
http://www.nationalacademies.org/history/members/chandrasekhar.html
SOURCE FROM:
http://www.nationalacademies.org/history/members/chandrasekhar.html
Wednesday, May 19, 2010
SCIENCE ACHIEVEMENT
Frederick Griffith
In 1928 Frederick Griffith, British microbiologist, made a series of unexpected observations while performing an experiment with the disease-causing bacteria pneumococcus and laboratory mice. Griffith's experiment dealt with two strains of the bacteria pneumococcus. One was a virulent strain with a smooth polysaccharide coat necessary for infection and colonies of this strain appear smooth. The other was a non-virulent strain with a rough coat that could not cause infection and colonies of the strain appear rough.
Griffith injected one group of mice with the smooth virulent strain and these mice died after a few days. He then injected another group with the rough non-virulent strain and these mice continued to be healthy. Griffith took a heat-killed strain of the virulent bacteria and injected it into mice and observed that they did not die. Griffith's fourth experiment was to inject heat treated, killed, smooth virulent strain mixed with the non virulent rough strain. He injected this mixture and found that after a few days the mice died. The blood of the dead mice showed high levels of virulent pneumococcus. Griffith theorized that some type of transformation takes place from the virulent to the non-virulent strain for it to synthesize a new polysaccharide coat.
GENETIC TRANSFER MATERIAL :DNA
Oswald Theodore Avery
Oswald Avery, Canadian physician and bacteriologist, found that the agent responsible for genetic transferring is the nucleic acid DNA and not protein as most biochemists theorized at the time. In 1944 Avery and his coworkers, McCarty and MacLeod, discovered the "transforming principle."
The Experiment
1.First they treated the bacteria with centafugation(BY CENTRIFUGAL), which eliminates large cellular pieces. The result: bacteria still transformed
2.Added protease(ENZIME), which removes all proteinsThe result: bacteria still transformed
3.Treated the bacteria with deoxyribonuclease(ENZIME), which eliminates all DNA The result: no transformation in the bacteria
The trio concluded that DNA is the cause of transformation, where in this experiment virulence is inherited.
John James Richard Macleod
James Macleod, the Scottish physiologist who is most known for his work on carbohydrate metabolism and insulin, was born on September 6, 1876 in Cluny, Scotland. He was the son of Reverend Robert Macleod. After his family moved to Aberdeen he attended Aberdeen Grammar School and then Marischal College of the University of Aberdeen to study medicine. In 1898 he obtained his medical degree with honors and was awarded the Anderson Traveling Fellowship. That year he published his first paper which was on the phosphorus content of muscle.
Macleod worked for a year at the Institute for Physiology at the University of Leipzig, Germany. The following year he was made demonstrator of Physiology at the London Hospital Medical School, and in 1902 was given the position of Lecturer in Biochemistry at the same school. That same year he was granted the McKinnon Research Studentship of the Royal Society until 1903 when appointed Professor of Physiology at the Western Reserve University at Cleveland, Ohio. In 1905 Macleod first became interested in carbohydrate metabolism especially in patients with the disease diabetes. He published thirty-seven papers on carbohydrate metabolism and an additional twelve papers on the experimentally produced glycosuria. He published a textbook on diabetes mellitus, the most common form of diabetes, which is the result of the body's failure to process the sugar glucose. When glucose can not be correctly stored and used, the level of glucose with the bloodstream rise, which cause serious complications. Diabetes mellitus was fatal during this time period.
During the winter session of 1916, Macleod was Professor of Physiology at McGill University, Montreal. In 1918 he was elected Professor of Physiology at the University of Toronto, Canada along with Director of the Physiological Laboratory and Associate Dean of the Faculty of Medicine. It was that this university that he did his work with insulin. Macleod and his research team found that the pancreas secretes insulin, which regulates the amount of glucose in the body's cells. Research revealed diabetes mellitus to be a failure of the pancreas to produce insulin. Frederick Banting, a Canadian surgeon came to Macleod in 1921 and asked for help in isolating insulin. He gave Banting laboratory access, dogs for experiment subject and medical student Charles Best as an assistant. Banting and Best performed a series of experiments, surgically changing the dog's pancreas. They extracted the insulin producing cells and then removed the insulin from these cells. They injected the insulin into the dog that was now artificially made diabetic. Observations showed that the injections controlled glucose levels in the dogs. Macleod and Canadian biochemist James Bertram Collip worked with Banting and Best to refine methods of removing and purifying insulin. In 1922, Banting and Best injected their insulin into a fourteen year old diabetic boy, which successfully treated his condition. Macleod publicly announced their discovery in February of 1922 and the patent for manufacturing of the pancreatic extract was approved. All financial proceeds of the patent went to the British Medical Research Council and the discoverers were given no payment. Banting and Macleod were jointly awarded the 1923 Nobel Prize for physiology or medicine. They both shared the prize money with Best and Collip.
Macleod was appointed Regius Professor of Physiology at the University of Aberdeen in 1928 and he held that position along with Consultant Physiologist to the Rowett Institute for Animal Nutrition until his death. Throughout his life, Macleod wrote eleven books and monographs. In 1932 he returned to his research and work on the possibility that the central nervous system plays a role in the cause of hyperglycemia. After experimenting on rabbits, Macleod concluded that stimulation of gluconeogenesis in the liver occurred via the parasympathetic nervous system. He also did work on air sickness, purine bases and electric shock. James Macleod died March 16, 1935.
Alfred Day Hershey
Alfred Hershey, the American geneticist, was born December 4, 1908 in Owosso, Michigan. He attended Michigan State University and in 1930 received his B. S. in chemistry and 1934 his Ph. D. in bacteriology. In that same year he was given the position of research assistant at the Department of Bacteriology of Washington University, St. Louis, Missouri. Hershey was promoted to instructor in 1936, assistant professor in 1938 and associate professor in 1942.
Throughout the 1940's Hershey worked with Italian microbiologist Salvador Edward Luria and German physicist Max Ludwig Henning Delbruck performing experiments with bacteriophages, which are viruses that infect bacteria. They organized the "Phage Group", a team of bacteriophage researchers who met every year at Cold Spring Harbor to discuss their work and advances. While Hershey and Delbruck were working together in 1946, they observed that when two different strains of bacteriophages have infected the same bacteria, the two viruses may exchange genetic information. They then produce offspring with different infective natures than either parent had. This was the first example of GENETIC RECOMBINATION in viruses.
He moved to Cold Spring Harbor, New York to join the Carnegie Institution of Washington's Department of Genetics in 1950. In 1952, Hershey and American geneticist Martha Chase performed their famous "blender experiment." Using a kitchen blender, they separated the protein coating from the bacteriophage's nucleic acid core. They injected nucleic acid into the bacterial cell and found that the acid itself caused replication and transmission of genetic information, not its protein components. This proved that genes are made of the nucleic acid DNA. One year later James Watson and Francis Crick announced the double-helix structure of DNA and a theory on how genetic material is passed. He then became director of the Carnegie Institution, renamed Genetic Research Unit at Cold Spring Harbor in 1962. Hershey's later research helped the development of vaccines for polio, measles and mumps. Hershey was awarded the 1969 Nobel Prize in physiology or medicine, along with Luria and Delbruck, for their discovery on the replication of viruses and their genetic structure. He retired from active research in 1972 but was a constant figure around the lab until his death in May of 1997.
SOURCE FROM:
http://library.thinkquest.org/20465/griffith.html
http://library.thinkquest.org/20465/avery.html
http://library.thinkquest.org/20465/macleod.html
http://library.thinkquest.org/20465/hershey.html
In 1928 Frederick Griffith, British microbiologist, made a series of unexpected observations while performing an experiment with the disease-causing bacteria pneumococcus and laboratory mice. Griffith's experiment dealt with two strains of the bacteria pneumococcus. One was a virulent strain with a smooth polysaccharide coat necessary for infection and colonies of this strain appear smooth. The other was a non-virulent strain with a rough coat that could not cause infection and colonies of the strain appear rough.
Griffith injected one group of mice with the smooth virulent strain and these mice died after a few days. He then injected another group with the rough non-virulent strain and these mice continued to be healthy. Griffith took a heat-killed strain of the virulent bacteria and injected it into mice and observed that they did not die. Griffith's fourth experiment was to inject heat treated, killed, smooth virulent strain mixed with the non virulent rough strain. He injected this mixture and found that after a few days the mice died. The blood of the dead mice showed high levels of virulent pneumococcus. Griffith theorized that some type of transformation takes place from the virulent to the non-virulent strain for it to synthesize a new polysaccharide coat.
GENETIC TRANSFER MATERIAL :DNA
Oswald Theodore Avery
Oswald Avery, Canadian physician and bacteriologist, found that the agent responsible for genetic transferring is the nucleic acid DNA and not protein as most biochemists theorized at the time. In 1944 Avery and his coworkers, McCarty and MacLeod, discovered the "transforming principle."
The Experiment
1.First they treated the bacteria with centafugation(BY CENTRIFUGAL), which eliminates large cellular pieces. The result: bacteria still transformed
2.Added protease(ENZIME), which removes all proteinsThe result: bacteria still transformed
3.Treated the bacteria with deoxyribonuclease(ENZIME), which eliminates all DNA The result: no transformation in the bacteria
The trio concluded that DNA is the cause of transformation, where in this experiment virulence is inherited.
John James Richard Macleod
James Macleod, the Scottish physiologist who is most known for his work on carbohydrate metabolism and insulin, was born on September 6, 1876 in Cluny, Scotland. He was the son of Reverend Robert Macleod. After his family moved to Aberdeen he attended Aberdeen Grammar School and then Marischal College of the University of Aberdeen to study medicine. In 1898 he obtained his medical degree with honors and was awarded the Anderson Traveling Fellowship. That year he published his first paper which was on the phosphorus content of muscle.
Macleod worked for a year at the Institute for Physiology at the University of Leipzig, Germany. The following year he was made demonstrator of Physiology at the London Hospital Medical School, and in 1902 was given the position of Lecturer in Biochemistry at the same school. That same year he was granted the McKinnon Research Studentship of the Royal Society until 1903 when appointed Professor of Physiology at the Western Reserve University at Cleveland, Ohio. In 1905 Macleod first became interested in carbohydrate metabolism especially in patients with the disease diabetes. He published thirty-seven papers on carbohydrate metabolism and an additional twelve papers on the experimentally produced glycosuria. He published a textbook on diabetes mellitus, the most common form of diabetes, which is the result of the body's failure to process the sugar glucose. When glucose can not be correctly stored and used, the level of glucose with the bloodstream rise, which cause serious complications. Diabetes mellitus was fatal during this time period.
During the winter session of 1916, Macleod was Professor of Physiology at McGill University, Montreal. In 1918 he was elected Professor of Physiology at the University of Toronto, Canada along with Director of the Physiological Laboratory and Associate Dean of the Faculty of Medicine. It was that this university that he did his work with insulin. Macleod and his research team found that the pancreas secretes insulin, which regulates the amount of glucose in the body's cells. Research revealed diabetes mellitus to be a failure of the pancreas to produce insulin. Frederick Banting, a Canadian surgeon came to Macleod in 1921 and asked for help in isolating insulin. He gave Banting laboratory access, dogs for experiment subject and medical student Charles Best as an assistant. Banting and Best performed a series of experiments, surgically changing the dog's pancreas. They extracted the insulin producing cells and then removed the insulin from these cells. They injected the insulin into the dog that was now artificially made diabetic. Observations showed that the injections controlled glucose levels in the dogs. Macleod and Canadian biochemist James Bertram Collip worked with Banting and Best to refine methods of removing and purifying insulin. In 1922, Banting and Best injected their insulin into a fourteen year old diabetic boy, which successfully treated his condition. Macleod publicly announced their discovery in February of 1922 and the patent for manufacturing of the pancreatic extract was approved. All financial proceeds of the patent went to the British Medical Research Council and the discoverers were given no payment. Banting and Macleod were jointly awarded the 1923 Nobel Prize for physiology or medicine. They both shared the prize money with Best and Collip.
Macleod was appointed Regius Professor of Physiology at the University of Aberdeen in 1928 and he held that position along with Consultant Physiologist to the Rowett Institute for Animal Nutrition until his death. Throughout his life, Macleod wrote eleven books and monographs. In 1932 he returned to his research and work on the possibility that the central nervous system plays a role in the cause of hyperglycemia. After experimenting on rabbits, Macleod concluded that stimulation of gluconeogenesis in the liver occurred via the parasympathetic nervous system. He also did work on air sickness, purine bases and electric shock. James Macleod died March 16, 1935.
Alfred Day Hershey
Alfred Hershey, the American geneticist, was born December 4, 1908 in Owosso, Michigan. He attended Michigan State University and in 1930 received his B. S. in chemistry and 1934 his Ph. D. in bacteriology. In that same year he was given the position of research assistant at the Department of Bacteriology of Washington University, St. Louis, Missouri. Hershey was promoted to instructor in 1936, assistant professor in 1938 and associate professor in 1942.
Throughout the 1940's Hershey worked with Italian microbiologist Salvador Edward Luria and German physicist Max Ludwig Henning Delbruck performing experiments with bacteriophages, which are viruses that infect bacteria. They organized the "Phage Group", a team of bacteriophage researchers who met every year at Cold Spring Harbor to discuss their work and advances. While Hershey and Delbruck were working together in 1946, they observed that when two different strains of bacteriophages have infected the same bacteria, the two viruses may exchange genetic information. They then produce offspring with different infective natures than either parent had. This was the first example of GENETIC RECOMBINATION in viruses.
He moved to Cold Spring Harbor, New York to join the Carnegie Institution of Washington's Department of Genetics in 1950. In 1952, Hershey and American geneticist Martha Chase performed their famous "blender experiment." Using a kitchen blender, they separated the protein coating from the bacteriophage's nucleic acid core. They injected nucleic acid into the bacterial cell and found that the acid itself caused replication and transmission of genetic information, not its protein components. This proved that genes are made of the nucleic acid DNA. One year later James Watson and Francis Crick announced the double-helix structure of DNA and a theory on how genetic material is passed. He then became director of the Carnegie Institution, renamed Genetic Research Unit at Cold Spring Harbor in 1962. Hershey's later research helped the development of vaccines for polio, measles and mumps. Hershey was awarded the 1969 Nobel Prize in physiology or medicine, along with Luria and Delbruck, for their discovery on the replication of viruses and their genetic structure. He retired from active research in 1972 but was a constant figure around the lab until his death in May of 1997.
SOURCE FROM:
http://library.thinkquest.org/20465/griffith.html
http://library.thinkquest.org/20465/avery.html
http://library.thinkquest.org/20465/macleod.html
http://library.thinkquest.org/20465/hershey.html
Sunday, May 16, 2010
BELOUSOV-ZHABOTINSKY REACTION
Belousov–Zhabotinsky reaction
A Belousov–Zhabotinsky reaction, or BZ reaction, is one of a class of reactions that serve as a classical example of non-equilibrium thermodynamics, resulting in the establishment of a nonlinear chemical oscillator. The only common element in these oscillating systems is the inclusion of bromine and an acid. The reactions are theoretically important in that they show that chemical reactions do not have to be dominated by equilibrium thermodynamic behavior. These reactions are far from equilibrium and remain so for a significant length of time. In this sense, they provide an interesting chemical model of nonequilibrium biological phenomena, and the mathematical models of the BZ reactions themselves are of theoretical interest.
An essential aspect of the BZ reaction is its so called "excitability" — under the influence of stimuli, patterns develop in what would otherwise be a perfectly quiescent medium. Some clock reactions such as Briggs–Rauscher and BZ using the chemical ruthenium bipyridyl as catalyst can be excited into self-organising activity through the influence of light.
The discovery of the phenomenon is credited to Boris Belousov. He noted, sometime in the 1950s (the dates change depending on source, but it ranges from 1951 to 1958), that in a mix of potassium bromate, cerium(IV) sulfate, propanedioic acid and citric acid in dilute sulfuric acid, the ratio of concentration of the cerium(IV) and cerium(III) ions oscillated, causing the colour of the solution to oscillate between a yellow solution and a colorless solution. This is due to the cerium(IV) ions being reduced by propanedioic acid to cerium(III) ions, which are then oxidized back to cerium(IV) ions by bromate(V) ions.
Belousov made two attempts to publish his finding, but was rejected on the grounds that he could not explain his results to the satisfaction of the editors of the journals to which he submitted his results. His work was finally published in a less respectable, non-reviewed journal.
Later, in 1961, a graduate student named Anatol Zhabotinsky rediscovered this reaction sequence;[2] however, the results of these men's work were still not widely disseminated, and were not known in the West until a conference in Prague in 1968.
There are a number of BZ cocktails available in the chemical literature and on the web. Ferroin, a complex of phenanthroline and iron is a common indicator. These reactions, if carried out in petri dishes, result in the formation first of colored spots. These spots grow into a series of expanding concentric rings or perhaps expanding spirals similar to the patterns generated by a cyclic cellular automaton. The colors disappear if the dishes are shaken, and then reappear. The waves continue until the reagents are consumed. The reaction can also be performed in a beaker using a magnetic stirrer.
Andrew Adamatzky, a computer scientist in the University of the West of England reported on liquid logic gates using the BZ reaction.
Investigators are also exploring the creation of a "wet computer", using self-creating "cells" and other techniques to mimic certain properties of neurons.
A Belousov–Zhabotinsky reaction, or BZ reaction, is one of a class of reactions that serve as a classical example of non-equilibrium thermodynamics, resulting in the establishment of a nonlinear chemical oscillator. The only common element in these oscillating systems is the inclusion of bromine and an acid. The reactions are theoretically important in that they show that chemical reactions do not have to be dominated by equilibrium thermodynamic behavior. These reactions are far from equilibrium and remain so for a significant length of time. In this sense, they provide an interesting chemical model of nonequilibrium biological phenomena, and the mathematical models of the BZ reactions themselves are of theoretical interest.
An essential aspect of the BZ reaction is its so called "excitability" — under the influence of stimuli, patterns develop in what would otherwise be a perfectly quiescent medium. Some clock reactions such as Briggs–Rauscher and BZ using the chemical ruthenium bipyridyl as catalyst can be excited into self-organising activity through the influence of light.
The discovery of the phenomenon is credited to Boris Belousov. He noted, sometime in the 1950s (the dates change depending on source, but it ranges from 1951 to 1958), that in a mix of potassium bromate, cerium(IV) sulfate, propanedioic acid and citric acid in dilute sulfuric acid, the ratio of concentration of the cerium(IV) and cerium(III) ions oscillated, causing the colour of the solution to oscillate between a yellow solution and a colorless solution. This is due to the cerium(IV) ions being reduced by propanedioic acid to cerium(III) ions, which are then oxidized back to cerium(IV) ions by bromate(V) ions.
Belousov made two attempts to publish his finding, but was rejected on the grounds that he could not explain his results to the satisfaction of the editors of the journals to which he submitted his results. His work was finally published in a less respectable, non-reviewed journal.
Later, in 1961, a graduate student named Anatol Zhabotinsky rediscovered this reaction sequence;[2] however, the results of these men's work were still not widely disseminated, and were not known in the West until a conference in Prague in 1968.
There are a number of BZ cocktails available in the chemical literature and on the web. Ferroin, a complex of phenanthroline and iron is a common indicator. These reactions, if carried out in petri dishes, result in the formation first of colored spots. These spots grow into a series of expanding concentric rings or perhaps expanding spirals similar to the patterns generated by a cyclic cellular automaton. The colors disappear if the dishes are shaken, and then reappear. The waves continue until the reagents are consumed. The reaction can also be performed in a beaker using a magnetic stirrer.
Andrew Adamatzky, a computer scientist in the University of the West of England reported on liquid logic gates using the BZ reaction.
Investigators are also exploring the creation of a "wet computer", using self-creating "cells" and other techniques to mimic certain properties of neurons.
MEDERMA FOR REDUCING SCAR
Mederma is an onion-extract-based topical gel produced by Merz Pharmaceuticals of Greensboro, North Carolina. Mederma's marketing claims it can make scars "softer, smoother, and less noticeable. One 2006 clinical trial found no statistically significant change in hypertrophic scar appearance from products of this type compared to the standard petrolatum emollient. while a 1999 pilot trial found an onion extract gel less effective than the petrolatum.
Though Mederma appears to do better than nothing at all, it does no better than cheap emollients which simply keep the skin moist.
Effectiveness
One 2006 clinical trial found no statistically significant change in hypertrophic scar appearance from products of this type compared to the standard petrolatum emollient. while a 1999 pilot trial found an onion extract gel less effective than the petrolatum. In 2010 a 54-person trial funded by Merz found that an onion extract cream improved the appearance of stretch marks.
Basic research and animal testing suggest the gel could be effective. A 1996 study into the therapeutic values of onion and garlic found that they may act as an anti-inflammatory and bacteriostatic and in 2002, researchers found that Mederma improved collagen organization after injury in rabbits.
Active Ingredient
Allium cepa, trademarked by Mederma as Cepalin (not to be confused with cephalin) is the active content of mederma derived from an onion called Allium cepa Linn[10], a readily available[11] and highly researched bioflavonoid with antihistamine and antiproliferative effects on both normal and malignant cells. This product is labeled as made in Germany, or originally developed in Germany.
Full Ingredients
Water (purified), PEG-4, Aloe Barbadensis Leaf Juice, Allium Cepa (Onion) Bulb Extract, Xanthan Gum, Allantoin, Methylparaben, Sorbic Acid, Fragrance.
Similar product
Merz Pharmaceuticals also produces Contractubex for scars, which also contains onion extract in addition to other ingredients. Contractubex has reportedly been found effective in clinical trials.
ADDITION:
WHAT IS ALLANTOIN?
Allantoin is a chemical compound with formula C4H6N4O3. It is also called 5-ureidohydantoin or glyoxyldiureide. It is a diureide of glyoxylic acid. Named after the allantois, an amniote embryonic excretory organ in which it concentrates during development in most mammals except humans and higher apes, it is a product of oxidation of uric acid by purine catabolism. After birth, it is the predominant means by which nitrogenous waste is excreted in the urine of these animals. In humans and higher apes, the metabolic pathway for conversion of uric acid to allantoin is not present, so the former is excreted. Recombinant rasburicase is sometimes used as a drug to catalyze this metabolic conversion in patients. In fish, allantoin is broken down further (into ammonia) before excretion. Allantoin is a major metabolic intermediate in many other organisms including plants and bacteria.
Applications
Allantoin is present in botanical extracts of the comfrey plant and urine from cows and most mammals. Chemically synthesized bulk allantoin is nature-identical, safe, NON-TOXIC,compatible with cosmetic raw materials and meets CTFA and JSCI requirements. Over 10,000 patents reference allantoin. Manufacturers cite several beneficial effects for allantoin as an active ingredient in over-the-counter cosmetics: a moisturizing and keratolytic effect, increasing the water content of the extracellular matrix and enhancing the desquamation of upper layers of dead skin cells, increasing the smoothness of the skin; promoting cell proliferation and wound healing; and a soothing, anti-irritant, and skin protectant effect by forming complexes with irritant and sensitizing agents. It is frequently present in toothpaste, mouthwash, and other oral hygiene products, in shampoos, lipsticks, anti-acne products, sun care products, and clarifying lotions, various cosmetic lotions and creams, and other cosmetic and pharmaceutical products.
WHAT IS METHYLPARABEN?
Parabens are a class of chemicals widely used as preservatives in the cosmetic and pharmaceutical industries. Parabens are effective preservatives in many types of formulas. These compounds, and their salts, are used primarily for their bactericidal and fungicidal properties. They can be found in shampoos, commercial moisturizers, shaving gels, personal lubricants, topical/parenteral pharmaceuticals, spray tanning solution and toothpaste. They are also used as food additives.
Their efficacy as preservatives, in combination with their low cost, their long history of safe use and the inefficacy of natural alternatives like grapefruit seed extract (GSE), probably explains why parabens are so commonplace. They are becoming increasingly controversial, however, and some organizations which adhere to the precautionary principle object to their everyday use.
Though Mederma appears to do better than nothing at all, it does no better than cheap emollients which simply keep the skin moist.
Effectiveness
One 2006 clinical trial found no statistically significant change in hypertrophic scar appearance from products of this type compared to the standard petrolatum emollient. while a 1999 pilot trial found an onion extract gel less effective than the petrolatum. In 2010 a 54-person trial funded by Merz found that an onion extract cream improved the appearance of stretch marks.
Basic research and animal testing suggest the gel could be effective. A 1996 study into the therapeutic values of onion and garlic found that they may act as an anti-inflammatory and bacteriostatic and in 2002, researchers found that Mederma improved collagen organization after injury in rabbits.
Active Ingredient
Allium cepa, trademarked by Mederma as Cepalin (not to be confused with cephalin) is the active content of mederma derived from an onion called Allium cepa Linn[10], a readily available[11] and highly researched bioflavonoid with antihistamine and antiproliferative effects on both normal and malignant cells. This product is labeled as made in Germany, or originally developed in Germany.
Full Ingredients
Water (purified), PEG-4, Aloe Barbadensis Leaf Juice, Allium Cepa (Onion) Bulb Extract, Xanthan Gum, Allantoin, Methylparaben, Sorbic Acid, Fragrance.
Similar product
Merz Pharmaceuticals also produces Contractubex for scars, which also contains onion extract in addition to other ingredients. Contractubex has reportedly been found effective in clinical trials.
ADDITION:
WHAT IS ALLANTOIN?
Allantoin is a chemical compound with formula C4H6N4O3. It is also called 5-ureidohydantoin or glyoxyldiureide. It is a diureide of glyoxylic acid. Named after the allantois, an amniote embryonic excretory organ in which it concentrates during development in most mammals except humans and higher apes, it is a product of oxidation of uric acid by purine catabolism. After birth, it is the predominant means by which nitrogenous waste is excreted in the urine of these animals. In humans and higher apes, the metabolic pathway for conversion of uric acid to allantoin is not present, so the former is excreted. Recombinant rasburicase is sometimes used as a drug to catalyze this metabolic conversion in patients. In fish, allantoin is broken down further (into ammonia) before excretion. Allantoin is a major metabolic intermediate in many other organisms including plants and bacteria.
Applications
Allantoin is present in botanical extracts of the comfrey plant and urine from cows and most mammals. Chemically synthesized bulk allantoin is nature-identical, safe, NON-TOXIC,compatible with cosmetic raw materials and meets CTFA and JSCI requirements. Over 10,000 patents reference allantoin. Manufacturers cite several beneficial effects for allantoin as an active ingredient in over-the-counter cosmetics: a moisturizing and keratolytic effect, increasing the water content of the extracellular matrix and enhancing the desquamation of upper layers of dead skin cells, increasing the smoothness of the skin; promoting cell proliferation and wound healing; and a soothing, anti-irritant, and skin protectant effect by forming complexes with irritant and sensitizing agents. It is frequently present in toothpaste, mouthwash, and other oral hygiene products, in shampoos, lipsticks, anti-acne products, sun care products, and clarifying lotions, various cosmetic lotions and creams, and other cosmetic and pharmaceutical products.
WHAT IS METHYLPARABEN?
Parabens are a class of chemicals widely used as preservatives in the cosmetic and pharmaceutical industries. Parabens are effective preservatives in many types of formulas. These compounds, and their salts, are used primarily for their bactericidal and fungicidal properties. They can be found in shampoos, commercial moisturizers, shaving gels, personal lubricants, topical/parenteral pharmaceuticals, spray tanning solution and toothpaste. They are also used as food additives.
Their efficacy as preservatives, in combination with their low cost, their long history of safe use and the inefficacy of natural alternatives like grapefruit seed extract (GSE), probably explains why parabens are so commonplace. They are becoming increasingly controversial, however, and some organizations which adhere to the precautionary principle object to their everyday use.
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