sábado, 16 de agosto de 2008
William Ross Ashby
" William Ross Ashby (1903-1972) was a British pioneer in the fields of Cybernetics and Systems Theory. He is best known for the Law of Requisite Variety, for his books Design for a Brain (1952) and An Introduction to Cybernetics (1956), and for building the Homeostat. "
Fonte do texto: <http://www.rossashby.info/index.html>.
Maiores informações em: <http://www.gwu.edu/~asc/biographies/ashby/ashby.html>.
Marcadores:
cibernética,
homeostease,
teoria dos sistemas
Ludwig Von Bertalanffy
Fonte do texto: <http://www.isss.org/lumLVB.htm>.
Sabine Brauckmann, University of Münster, January 1999
" Ludwig von Bertalanffy was born in a little village near Vienna on September 19, 1901. In 1918 he started his studies with history of art and philosophy, firstly at the University of Innsbruck and then at the University of Vienna where he became a pupil of the philosophers Robert Reininger and Moritz Schlick, one of the founders of the Viennese Circle. He finished his PhD with a thesis on the German physicist and philosopher Gustav Theodor Fechner in 1926, and published his first book on theoretical biology two years later (Modern Theories of Development).
In this critical review of morphogenetic theories Bertalanffy tried to solve the crucial issue of reduction, namely, whether the categories of biology are different from the physical ones, or whether an absolute reduction from the biological domain to the physical one is possible at all. He resolved this enigma with the organismic system theory that assigns to the biological systems a self-organizational dynamics. The organismic system theory should experimentally investigate how the pattern formation functions (1929, 1931). For it, he developed the kinetic theory of open systems characteristics of which are equifinality and steady state. His main goal was to unite metabolism, growth, morphogenesis and sense physiology to a dynamic theory of stationary open systems (1933, 1938).
In 1934 he was habilitated by Reininger, Schlick and the zoologist Versluys for the first volume of his Theoretische Biologie. The monography postulated two essential aims of a theoretical biology, firstly to clean up the conceptual terminology of biology, and, secondly, to explain how the phenomena of life can spontaneously emerge from forces existing inside an organism. Here the organismic system represented the main problem as well as the still-to-formulate program of a theoretical biology. The second volume developed the research program of a dynamic morphology and applied the mathematical method to biological problems.
As a Rockefeller Fellow at the University of Chicago (1937-38) he worked with the Russian physicist Nicolaus Rashevsky. There he gave his first lecture about the General System Theory as a methodology that is valid for all sciences (1949b). In 1939 he was appointed to an extraordinary professor at the University of Vienna. There Bertalanffy concentrated his research on a comparative physiology of growth. He was the first biologist who held lectures in zoology for students of medicine and an integrated course on botany and zoology. During this time he wrote, beneath his most programmatic article on organisms as physical systems (1940), the summary of his biological reasoning: Problems of Life.
In 1949 he emigrated to Canada where he mainly worked on metabolism, growth, biophysics, and cancer cytology. In his biomedical research on cancer he developed, with his son Felix, the Bertalanffy-method of cancer cytodiagnosis. From the 1950's onwards he shifted his research from the biological sciences to the methodology of science, the General System Theory (GST), and cognitive psychology. Based on his humanistic worldview, he developed a holistic epistemology (1966) which sharply criticized the machine metaphor of neobehaviorism (Robots).
In 1960 he was appointed a Professor for Theoretical Biology of the Department of Zoology and Psychology at the University of Alberta in Edmonton (Canada). There Bertalanffy, the psychologist Royce and the philosopher Tenneysen established the Advanced Center for Theoretical Psychology that became a center for cognitive psychology over the next 30 years. In that time his system theoretical approach focused on the modern world of technology that has thrown us humans out of nature and has isolated us from each other. To overcome this Vereinzelung, Bertalanffy emphasized in his later works the importance of the symbolic worlds of culture which we ourselves have created during evolution.
After his retirement he became a Professor of the Faculty of Social Sciences at the State University of New York (SUNY). An international symposium celebrated his 70th birthday in 1971. In June 1972, he suffered a heart stroke and died a few days later, on June 12, shortly after midnight.
To sum up his life-work, Bertalanffy wrote 13 monographies, four anthologies, over 200 articles, he was the chief editor of the Handbuch der Biologie--among many others. His themes encompassed theoretical biology and experimental physiology (Bertalanffy equations), theoretical psychology--particularly in the last two decades of his life--, cancer research (Bertalanffy method of cancercytodiagnosis), and philosophy and history of science.
No doubt, the person Bertalanffy was a very fascinating one, proud of his European background, a connoisseur of architectural drawings, Japanese woodcuts, and stamps, who loved to hear the music of Mozart and Beethoven and to become absorbed in the works of Goethe. Sometimes he puzzled his environment by sarcastic remarks, or his black sense of humor. His worldview was an old-fashioned, however, never outdated one that was deeply rooted in a humanistic ethos:
"In the last resort, however, it is always a system of values, of ideas, of ideologies - choose whatever word you like - that is decisive.'' (1964b:245)
Already in the 1930's Bertalanffy formulated the organismic system theory that later became the kernel of the GST (1949b, 1960a). His starting point was to deduce the phenomena of life from a spontaneous grouping of system forces--comparable, for instance, to the system developmental biology nowadays. He based his approach on the phenomenal assumption that there exists a dynamical process inside the organic system. In the next step he modelled the heuristic fiction of the organism as an open system striving towards a steady state. Then he postulated two biological principles, namely, the maintenance of the organism in the non-equilibrium, and the hierarchic organization of a systemic structure. Finally he furnished this biological system theory with a research program that dealt with the quantitative kinetic of growth and metabolism.
In the 1940's he conducted his theory of open systems from a thermodynamical point--a similar approach as the thermodynamics of irreversible processes as developed by Prigogine at the same time. As opposed to a closed system in a kinetic reversible equilibrium, a dynamically irreversible steady state determines an open. By it the process rates of the specific components are exactly synchronisized to one another as well as to the Eigengeschwindigkeit of the complex whole. The general system shows a kind of self-regulation comparable to the behavior of an organic system. For example, if you observe the energy flow of an open system, it tends towards a steady state because that phase corresponds to a minimum entropy production enduring the systems conditions. The minimum production stabilizes the system structure and the dynamics of streams and flows. Thus, the system will achieve the dissipative state that configures a structure since it maintains itself in a state far from equilibrium (cf. ffe-systems).
As a metatheory derived from both theories, Bertalanffy introduced the GST as a new paradigm which should control the model construction in all the sciences (1949c:45). As opposed to the mathematical system theory, it describes its models in a qualitative and non-formalized language. Thus, its task was a very broad one, namely, to deduce the universal principles which are valid for systems in general. In a first step he reformulated the classical concept of the system and determined it as a category by which we know the relations between objects and phenomena.
The new system concept now represents a set of interrelated components, a complex entity in space-time which shows structural similarities (isomorphisms). It constitutes itself in such a way that the systemic particles maintain their structure by an assemblage process and tend to restore themselves after disturbances--analogous to the features of a living organism. Since those isomorphisms exist between living organisms, cybernetic machines, and social systems, one can simulate interdisciplinary models and transfer the data of a scientific realm to another one.
As a methodology, applicable to all sciences, the GST encompasses the cybernetic theory of feedback that represents a special class of self-regulating systems (1964:15). According to Bertalanffy, there exists a fundamental difference between the GST and cybernetics since feedback mechanisms are controlled by constraints whilst the dynamical systems are showing the free interplay of forces. Moreover, the regulative mechanisms of cybernetic machines are based on pre-determined structures. In short, the GST is a regulative instruction that, for instance, synthetizes the data, or even laws, of the natural sciences, applicable to all the other sciences.
The greatest merit of Bertalanffy, beneath his outstanding work on theoretical biology, was to have pushed forward the development of the modern system theories that nowadays study non-stationary structures and the dynamics of self-organization. Instead of a conclusion, the last words will belong to Bertalanffy himself:
'... this shows the existence of a general systems theory which deals with formal characteristics of systems, concrete facts appearing as their special applications by defining variables and parameters. In still other terms, such examples show a formal uniformity of nature.' GST:62 "
Maiores informações em:
BORGES, Maria Alice Guimarães. A compreensão da sociedade da informação. Ci. Inf. , Brasília, v. 29, n. 3, dez. 2000. Disponível em: <http://www.scielo.br/scielo.php?pid=S0100-19652000000300003&script=sci_arttext&tlng=es>. Acesso em: 22 Nov. 2008.
Marcadores:
biologia,
Ludwig von Bertalanffy,
pensamento sistêmico,
sistemas
James Ephraim Lovelock
" James Ephraim Lovelock was born on 26 July 1919 in Letchworth Garden City in the United Kingdom. He graduated as a chemist from Manchester University in 1941 and in 1948 received a Ph.D. degree in medicine from the London School of Hygiene and Tropical Medicine. In 1959 he received the D.Sc. degree in biophysics from London University. After graduating from Manchester he started employment with the Medical Research Council at the National Institute for Medical Research in London.
In 1954 he was awarded the Rockefeller Travelling Fellowship in Medicine and chose to spend it at Harvard University Medical School in Boston. In 1958 he visited Yale University for a similar period. He resigned from the National Institute in London in 1961 to take up full time employment as Professor of Chemistry at Baylor University College of Medicine in Houston, Texas, where he remained until 1964. During his stay in Texas he collaborated with colleagues at the Jet Propulsion Laboratory, Pasadena, California on Lunar and Planetary Research.
Since 1964 he has conducted an independent practice in science, although continuing honorary academic associations as a visiting professor, first at the University of Houston and then at the University of Reading in the U.K. Since 1982 he has been associated with the Marine Biological Association at Plymouth, first as a council member, and from 1986 to 1990 as its president.
James Lovelock is the author of more than 200 scientific papers, distributed almost equally among topics in Medicine, Biology, Instrument and Atmospheric Science and Geophysiology. He has applied for more than 40 patents, mostly for detectors for use in chemical analysis.
One of these, the electron capture detector (ECD), was important in the development of environmental awareness. It confirmed the ubiquitous distribution of pesticide residues and other halogen bearing chemicals. This information, together with Rachel Carson's seminal book, Silent Spring, is often said to have initiated the awareness of environmental disturbance. Later the ECD enabled the discovery of the PCBs in the natural environment. More recently it was responsible for the discovery of the global distribution of nitrous oxide and of the chlorofluorocarbons, both of which are important in the stratospheric chemistry of ozone. Some of his inventions were adopted by NASA in their programme of planetary exploration. He was awarded by NASA three Certificates of Recognition for these.
He is the originator of the Gaia Hypothesis (now Gaia Theory) and has written three books on the subject: Gaia: a new look at life on Earth (Oxford University Press, 1979); The Ages of Gaia (WW Norton, 1988); Gaia: the practical science of planetary medicine (Gaia Books, 1991); and an autobiography, Homage to Gaia (Oxford University Press, 2000). His latest book is The Revenge of Gaia (Allen Lane/Penguin 2006).
He was elected a Fellow of the Royal Society in 1974 and in 1975 received the Tswett Medal for Chromatography. Earlier he received a CIBA Foundation Prize for research into Ageing. In 1980 he received the American Chemical Society's award for Chromatography and in 1986 the Silver Medal and Prize of the Plymouth Marine Laboratory. In 1988 he was a recipient of the Norbert Gerbier Prize of the World Meteorological Organization, and in 1990 was awarded the first Amsterdam Prize for the Environment by the Royal Netherlands Academy of Arts and Sciences. In 1996 he received the Volvo Prize for the Environment and in 1997 the Blue Planet Prize. He has received honorary Doctorates in Science from the University East Anglia 1982, Exeter University 1988, Plymouth Polytechnic (now Plymouth University) 1988, Stockholm University 1991, University of Edinburgh 1993, University of Kent 1996 and the University of Colorado (at Boulder) 1997. He was made a C.B.E. in 1990, and in 2003 a Companion of Honour by Her Majesty the Queen.
James Lovelock's first interest is the Life Sciences, originally as Medical Research but more recently in Geophysiology, the systems science of the Earth. His second interest that of instrument design and development, has often interacted with the first to their mutual benefit.
He has been since 1994 an Honorary Visiting Fellow of Green College, University of Oxford. "
Fonte do texto: <http://www.jameslovelock.org/page2.html>.
Maiores informações em: <http://www.jameslovelock.org/>.
Marcadores:
James Lovelock,
Teoria de Gaia
Lynn Margulis
" Lynn Margulis is Distinguished University Professor in the Department of Geosciences at the University of Massachusetts, Amherst. She was elected to the National Academy of Sciences in 1983, received from William J. Clinton the Presidential Medal of Science in 1999. The Library of Congress, Washington, D.C., announced in 1998 that it will permanently archive her papers. She was a faculty mentor at Boston University for 22 years.
Her publications, spanning a wide range of scientific topics, include original contributions to cell biology and microbial evolution. She is best known for her theory of symbiogenesis, which challenges a central tenet of neodarwinism. She argues that inherited variation, significant in evolution, does not come mainly from random mutations. Rather new tissues, organs, and even new species evolve primarily through the long-lasting intimacy of strangers. The fusion of genomes in symbioses followed by natural selection, she suggests, leads to increasingly complex levels of individuality. Dr. Margulis is also acknowledged for her contribution to James E. Lovelock’s Gaia concept. Gaia theory posits that the Earth’s surface interactions among living beings sediment, air, and water have created a vast self-regulating system.
Professor Margulis, who participates in hands-on teaching activities at levels from middle to graduate school, is the author of many articles and books. The most recent include Symbiotic Planet: A new look at evolution (1998) and Acquiring Genomes: A theory of the origins of species (2002), co-written with Dorion Sagan. Indeed, over the past decade and a half, Professor Margulis has co-written a number of books with Sagan, among them What is Sex? (1997), What is Life? (1995), Mystery Dance: On the evolution of human sexuality (1991), Microcosmos: Four billion years of evolution from our microbial ancestors (1986), and Origins of Sex: Three billion years of genetic recombination (1986). Her work with K. V. Schwartz provides a consistent formal classification of all life on Earth and has lead to the third edition of Five Kingdoms: An illustrated guide to the phyla of life on Earth (1998). Their evolutionary classification scheme was generated from scientific results of numerous colleagues. The logical basis for it is summarized in her single-authored book Symbiosis in Cell Evolution: Microbial communities in the Archean and Proterozoic eons (second edition, 1993). The bacterial origins of both chloroplasts and mitochondria are established. At present she works on the possible origin of cilia from spirochetes. "
Fonte do texto: <http://www.geo.umass.edu/faculty/margulis/>
Mais informações disponíveis em:
Marcadores:
Lynn Margulis,
Sistemas auto-regulatórios,
teoria da simbiogênese
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